Today, 20211202 (2nd December 2021), is a palindrome in the YYYYMMDD format. It is the 83rd of what will ultimately be 366 palindromic dates in this format.
Dates of this format come in waves separated by huge gaps. There were no palindromic dates of this format between 13800831 (31st August 1380) and 20011002 (2nd October 2001). Between 2001 and 22900922 (22nd September 2290), we can expect about one every ten years. Then a similarly huge gap appears until 30011003 (3rd October 3001). This repeating millennium-long pattern, of a few centuries of about one per decade followed by many more centuries of nothing, has been visible since the epoch, and will continue fairly regularly until the year number hits five digits.
(For the record, the best date format is not YYYYMMDD but YYYY-MM-DD, which is always totally unambiguous and allows lexicographical sorting. Dates in this format are never palindromic, due to the placement of the hyphens.)
Every possible birthday appears in this listing exactly once! To figure out yours,
# | YYYYMMDD | DDs MMMM YYYY | Days until next |
---|---|---|---|
1 | 01011010 | 10th October 101 | 3014 |
2 | 01100110 | 10th January 110 | 669 |
3 | 01111110 | 10th November 111 | 3014 |
4 | 01200210 | 10th February 120 | 669 |
5 | 01211210 | 10th December 121 | 3012 |
6 | 01300310 | 10th March 130 | 3684 |
7 | 01400410 | 10th April 140 | 3682 |
8 | 01500510 | 10th May 150 | 3684 |
9 | 01600610 | 10th June 160 | 3682 |
10 | 01700710 | 10th July 170 | 3684 |
11 | 01800810 | 10th August 180 | 3683 |
12 | 01900910 | 10th September 190 | 4057 |
13 | 02011020 | 20th October 201 | 3014 |
14 | 02100120 | 20th January 210 | 669 |
15 | 02111120 | 20th November 211 | 3014 |
16 | 02200220 | 20th February 220 | 669 |
17 | 02211220 | 20th December 221 | 3012 |
18 | 02300320 | 20th March 230 | 3684 |
19 | 02400420 | 20th April 240 | 3682 |
20 | 02500520 | 20th May 250 | 3684 |
21 | 02600620 | 20th June 260 | 3682 |
22 | 02700720 | 20th July 270 | 3684 |
23 | 02800820 | 20th August 280 | 3683 |
24 | 02900920 | 20th September 290 | 4057 |
25 | 03011030 | 30th October 301 | 3014 |
26 | 03100130 | 30th January 310 | 669 |
27 | 03111130 | 30th November 311 | 3683 |
28 | 03211230 | 30th December 321 | 3012 |
29 | 03300330 | 30th March 330 | 3684 |
30 | 03400430 | 30th April 340 | 3682 |
31 | 03500530 | 30th May 350 | 3684 |
32 | 03600630 | 30th June 360 | 3682 |
33 | 03700730 | 30th July 370 | 3684 |
34 | 03800830 | 30th August 380 | 3683 |
35 | 03900930 | 30th September 390 | 223164 |
36 | 10011001 | 1st October 1001 | 3014 |
37 | 10100101 | 1st January 1010 | 669 |
38 | 10111101 | 1st November 1011 | 3014 |
39 | 10200201 | 1st February 1020 | 669 |
40 | 10211201 | 1st December 1021 | 3012 |
41 | 10300301 | 1st March 1030 | 3684 |
42 | 10400401 | 1st April 1040 | 3682 |
43 | 10500501 | 1st May 1050 | 3684 |
44 | 10600601 | 1st June 1060 | 3682 |
45 | 10700701 | 1st July 1070 | 3684 |
46 | 10800801 | 1st August 1080 | 3683 |
47 | 10900901 | 1st September 1090 | 4057 |
48 | 11011011 | 11th October 1101 | 3014 |
49 | 11100111 | 11th January 1110 | 669 |
50 | 11111111 | 11th November 1111 | 3014 |
51 | 11200211 | 11th February 1120 | 669 |
52 | 11211211 | 11th December 1121 | 3012 |
53 | 11300311 | 11th March 1130 | 3684 |
54 | 11400411 | 11th April 1140 | 3682 |
55 | 11500511 | 11th May 1150 | 3684 |
56 | 11600611 | 11th June 1160 | 3682 |
57 | 11700711 | 11th July 1170 | 3684 |
58 | 11800811 | 11th August 1180 | 3683 |
59 | 11900911 | 11th September 1190 | 4058 |
60 | 12011021 | 21st October 1201 | 3014 |
61 | 12100121 | 21st January 1210 | 669 |
62 | 12111121 | 21st November 1211 | 3014 |
63 | 12200221 | 21st February 1220 | 669 |
64 | 12211221 | 21st December 1221 | 3012 |
65 | 12300321 | 21st March 1230 | 3684 |
66 | 12400421 | 21st April 1240 | 3682 |
67 | 12500521 | 21st May 1250 | 3684 |
68 | 12600621 | 21st June 1260 | 3682 |
69 | 12700721 | 21st July 1270 | 3684 |
70 | 12800821 | 21st August 1280 | 3683 |
71 | 12900921 | 21st September 1290 | 4057 |
72 | 13011031 | 31st October 1301 | 3014 |
73 | 13100131 | 31st January 1310 | 4352 |
74 | 13211231 | 31st December 1321 | 3012 |
75 | 13300331 | 31st March 1330 | 7366 |
76 | 13500531 | 31st May 1350 | 7366 |
77 | 13700731 | 31st July 1370 | 3684 |
78 | 13800831 | 31st August 1380 | 226847 |
79 | 20011002 | 2nd October 2001 | 3014 |
80 | 20100102 | 2nd January 2010 | 669 |
81 | 20111102 | 2nd November 2011 | 3014 |
82 | 20200202 | 2nd February 2020 | 669 |
83 | 20211202 | 2nd December 2021 | 3012 |
84 | 20300302 | 2nd March 2030 | 3684 |
85 | 20400402 | 2nd April 2040 | 3682 |
86 | 20500502 | 2nd May 2050 | 3684 |
87 | 20600602 | 2nd June 2060 | 3682 |
88 | 20700702 | 2nd July 2070 | 3684 |
89 | 20800802 | 2nd August 2080 | 3683 |
90 | 20900902 | 2nd September 2090 | 4057 |
91 | 21011012 | 12th October 2101 | 3014 |
92 | 21100112 | 12th January 2110 | 669 |
93 | 21111112 | 12th November 2111 | 3014 |
94 | 21200212 | 12th February 2120 | 669 |
95 | 21211212 | 12th December 2121 | 3012 |
96 | 21300312 | 12th March 2130 | 3684 |
97 | 21400412 | 12th April 2140 | 3682 |
98 | 21500512 | 12th May 2150 | 3684 |
99 | 21600612 | 12th June 2160 | 3682 |
100 | 21700712 | 12th July 2170 | 3684 |
101 | 21800812 | 12th August 2180 | 3683 |
102 | 21900912 | 12th September 2190 | 4057 |
103 | 22011022 | 22nd October 2201 | 3014 |
104 | 22100122 | 22nd January 2210 | 669 |
105 | 22111122 | 22nd November 2211 | 3014 |
106 | 22200222 | 22nd February 2220 | 669 |
107 | 22211222 | 22nd December 2221 | 3012 |
108 | 22300322 | 22nd March 2230 | 3684 |
109 | 22400422 | 22nd April 2240 | 3682 |
110 | 22500522 | 22nd May 2250 | 3684 |
111 | 22600622 | 22nd June 2260 | 3682 |
112 | 22700722 | 22nd July 2270 | 3684 |
113 | 22800822 | 22nd August 2280 | 3683 |
114 | 22900922 | 22nd September 2290 | 259698 |
115 | 30011003 | 3rd October 3001 | 3014 |
116 | 30100103 | 3rd January 3010 | 669 |
117 | 30111103 | 3rd November 3011 | 3014 |
118 | 30200203 | 3rd February 3020 | 669 |
119 | 30211203 | 3rd December 3021 | 3012 |
120 | 30300303 | 3rd March 3030 | 3684 |
121 | 30400403 | 3rd April 3040 | 3682 |
122 | 30500503 | 3rd May 3050 | 3684 |
123 | 30600603 | 3rd June 3060 | 3682 |
124 | 30700703 | 3rd July 3070 | 3684 |
125 | 30800803 | 3rd August 3080 | 3683 |
126 | 30900903 | 3rd September 3090 | 4057 |
127 | 31011013 | 13th October 3101 | 3014 |
128 | 31100113 | 13th January 3110 | 669 |
129 | 31111113 | 13th November 3111 | 3014 |
130 | 31200213 | 13th February 3120 | 669 |
131 | 31211213 | 13th December 3121 | 3012 |
132 | 31300313 | 13th March 3130 | 3684 |
133 | 31400413 | 13th April 3140 | 3682 |
134 | 31500513 | 13th May 3150 | 3684 |
135 | 31600613 | 13th June 3160 | 3682 |
136 | 31700713 | 13th July 3170 | 3684 |
137 | 31800813 | 13th August 3180 | 3683 |
138 | 31900913 | 13th September 3190 | 4058 |
139 | 32011023 | 23rd October 3201 | 3014 |
140 | 32100123 | 23rd January 3210 | 669 |
141 | 32111123 | 23rd November 3211 | 3014 |
142 | 32200223 | 23rd February 3220 | 669 |
143 | 32211223 | 23rd December 3221 | 3012 |
144 | 32300323 | 23rd March 3230 | 3684 |
145 | 32400423 | 23rd April 3240 | 3682 |
146 | 32500523 | 23rd May 3250 | 3684 |
147 | 32600623 | 23rd June 3260 | 3682 |
148 | 32700723 | 23rd July 3270 | 3684 |
149 | 32800823 | 23rd August 3280 | 3683 |
150 | 32900923 | 23rd September 3290 | 259698 |
151 | 40011004 | 4th October 4001 | 3014 |
152 | 40100104 | 4th January 4010 | 669 |
153 | 40111104 | 4th November 4011 | 3014 |
154 | 40200204 | 4th February 4020 | 669 |
155 | 40211204 | 4th December 4021 | 3012 |
156 | 40300304 | 4th March 4030 | 3684 |
157 | 40400404 | 4th April 4040 | 3682 |
158 | 40500504 | 4th May 4050 | 3684 |
159 | 40600604 | 4th June 4060 | 3682 |
160 | 40700704 | 4th July 4070 | 3684 |
161 | 40800804 | 4th August 4080 | 3683 |
162 | 40900904 | 4th September 4090 | 4057 |
163 | 41011014 | 14th October 4101 | 3014 |
164 | 41100114 | 14th January 4110 | 669 |
165 | 41111114 | 14th November 4111 | 3014 |
166 | 41200214 | 14th February 4120 | 669 |
167 | 41211214 | 14th December 4121 | 3012 |
168 | 41300314 | 14th March 4130 | 3684 |
169 | 41400414 | 14th April 4140 | 3682 |
170 | 41500514 | 14th May 4150 | 3684 |
171 | 41600614 | 14th June 4160 | 3682 |
172 | 41700714 | 14th July 4170 | 3684 |
173 | 41800814 | 14th August 4180 | 3683 |
174 | 41900914 | 14th September 4190 | 4057 |
175 | 42011024 | 24th October 4201 | 3014 |
176 | 42100124 | 24th January 4210 | 669 |
177 | 42111124 | 24th November 4211 | 3014 |
178 | 42200224 | 24th February 4220 | 669 |
179 | 42211224 | 24th December 4221 | 3012 |
180 | 42300324 | 24th March 4230 | 3684 |
181 | 42400424 | 24th April 4240 | 3682 |
182 | 42500524 | 24th May 4250 | 3684 |
183 | 42600624 | 24th June 4260 | 3682 |
184 | 42700724 | 24th July 4270 | 3684 |
185 | 42800824 | 24th August 4280 | 3683 |
186 | 42900924 | 24th September 4290 | 259698 |
187 | 50011005 | 5th October 5001 | 3014 |
188 | 50100105 | 5th January 5010 | 669 |
189 | 50111105 | 5th November 5011 | 3014 |
190 | 50200205 | 5th February 5020 | 669 |
191 | 50211205 | 5th December 5021 | 3012 |
192 | 50300305 | 5th March 5030 | 3684 |
193 | 50400405 | 5th April 5040 | 3682 |
194 | 50500505 | 5th May 5050 | 3684 |
195 | 50600605 | 5th June 5060 | 3682 |
196 | 50700705 | 5th July 5070 | 3684 |
197 | 50800805 | 5th August 5080 | 3683 |
198 | 50900905 | 5th September 5090 | 4057 |
199 | 51011015 | 15th October 5101 | 3014 |
200 | 51100115 | 15th January 5110 | 669 |
201 | 51111115 | 15th November 5111 | 3014 |
202 | 51200215 | 15th February 5120 | 669 |
203 | 51211215 | 15th December 5121 | 3012 |
204 | 51300315 | 15th March 5130 | 3684 |
205 | 51400415 | 15th April 5140 | 3682 |
206 | 51500515 | 15th May 5150 | 3684 |
207 | 51600615 | 15th June 5160 | 3682 |
208 | 51700715 | 15th July 5170 | 3684 |
209 | 51800815 | 15th August 5180 | 3683 |
210 | 51900915 | 15th September 5190 | 4058 |
211 | 52011025 | 25th October 5201 | 3014 |
212 | 52100125 | 25th January 5210 | 669 |
213 | 52111125 | 25th November 5211 | 3014 |
214 | 52200225 | 25th February 5220 | 669 |
215 | 52211225 | 25th December 5221 | 3012 |
216 | 52300325 | 25th March 5230 | 3684 |
217 | 52400425 | 25th April 5240 | 3682 |
218 | 52500525 | 25th May 5250 | 3684 |
219 | 52600625 | 25th June 5260 | 3682 |
220 | 52700725 | 25th July 5270 | 3684 |
221 | 52800825 | 25th August 5280 | 3683 |
222 | 52900925 | 25th September 5290 | 259698 |
223 | 60011006 | 6th October 6001 | 3014 |
224 | 60100106 | 6th January 6010 | 669 |
225 | 60111106 | 6th November 6011 | 3014 |
226 | 60200206 | 6th February 6020 | 669 |
227 | 60211206 | 6th December 6021 | 3012 |
228 | 60300306 | 6th March 6030 | 3684 |
229 | 60400406 | 6th April 6040 | 3682 |
230 | 60500506 | 6th May 6050 | 3684 |
231 | 60600606 | 6th June 6060 | 3682 |
232 | 60700706 | 6th July 6070 | 3684 |
233 | 60800806 | 6th August 6080 | 3683 |
234 | 60900906 | 6th September 6090 | 4057 |
235 | 61011016 | 16th October 6101 | 3014 |
236 | 61100116 | 16th January 6110 | 669 |
237 | 61111116 | 16th November 6111 | 3014 |
238 | 61200216 | 16th February 6120 | 669 |
239 | 61211216 | 16th December 6121 | 3012 |
240 | 61300316 | 16th March 6130 | 3684 |
241 | 61400416 | 16th April 6140 | 3682 |
242 | 61500516 | 16th May 6150 | 3684 |
243 | 61600616 | 16th June 6160 | 3682 |
244 | 61700716 | 16th July 6170 | 3684 |
245 | 61800816 | 16th August 6180 | 3683 |
246 | 61900916 | 16th September 6190 | 4057 |
247 | 62011026 | 26th October 6201 | 3014 |
248 | 62100126 | 26th January 6210 | 669 |
249 | 62111126 | 26th November 6211 | 3014 |
250 | 62200226 | 26th February 6220 | 669 |
251 | 62211226 | 26th December 6221 | 3012 |
252 | 62300326 | 26th March 6230 | 3684 |
253 | 62400426 | 26th April 6240 | 3682 |
254 | 62500526 | 26th May 6250 | 3684 |
255 | 62600626 | 26th June 6260 | 3682 |
256 | 62700726 | 26th July 6270 | 3684 |
257 | 62800826 | 26th August 6280 | 3683 |
258 | 62900926 | 26th September 6290 | 259698 |
259 | 70011007 | 7th October 7001 | 3014 |
260 | 70100107 | 7th January 7010 | 669 |
261 | 70111107 | 7th November 7011 | 3014 |
262 | 70200207 | 7th February 7020 | 669 |
263 | 70211207 | 7th December 7021 | 3012 |
264 | 70300307 | 7th March 7030 | 3684 |
265 | 70400407 | 7th April 7040 | 3682 |
266 | 70500507 | 7th May 7050 | 3684 |
267 | 70600607 | 7th June 7060 | 3682 |
268 | 70700707 | 7th July 7070 | 3684 |
269 | 70800807 | 7th August 7080 | 3683 |
270 | 70900907 | 7th September 7090 | 4057 |
271 | 71011017 | 17th October 7101 | 3014 |
272 | 71100117 | 17th January 7110 | 669 |
273 | 71111117 | 17th November 7111 | 3014 |
274 | 71200217 | 17th February 7120 | 669 |
275 | 71211217 | 17th December 7121 | 3012 |
276 | 71300317 | 17th March 7130 | 3684 |
277 | 71400417 | 17th April 7140 | 3682 |
278 | 71500517 | 17th May 7150 | 3684 |
279 | 71600617 | 17th June 7160 | 3682 |
280 | 71700717 | 17th July 7170 | 3684 |
281 | 71800817 | 17th August 7180 | 3683 |
282 | 71900917 | 17th September 7190 | 4058 |
283 | 72011027 | 27th October 7201 | 3014 |
284 | 72100127 | 27th January 7210 | 669 |
285 | 72111127 | 27th November 7211 | 3014 |
286 | 72200227 | 27th February 7220 | 669 |
287 | 72211227 | 27th December 7221 | 3012 |
288 | 72300327 | 27th March 7230 | 3684 |
289 | 72400427 | 27th April 7240 | 3682 |
290 | 72500527 | 27th May 7250 | 3684 |
291 | 72600627 | 27th June 7260 | 3682 |
292 | 72700727 | 27th July 7270 | 3684 |
293 | 72800827 | 27th August 7280 | 3683 |
294 | 72900927 | 27th September 7290 | 259698 |
295 | 80011008 | 8th October 8001 | 3014 |
296 | 80100108 | 8th January 8010 | 669 |
297 | 80111108 | 8th November 8011 | 3014 |
298 | 80200208 | 8th February 8020 | 669 |
299 | 80211208 | 8th December 8021 | 3012 |
300 | 80300308 | 8th March 8030 | 3684 |
301 | 80400408 | 8th April 8040 | 3682 |
302 | 80500508 | 8th May 8050 | 3684 |
303 | 80600608 | 8th June 8060 | 3682 |
304 | 80700708 | 8th July 8070 | 3684 |
305 | 80800808 | 8th August 8080 | 3683 |
306 | 80900908 | 8th September 8090 | 4057 |
307 | 81011018 | 18th October 8101 | 3014 |
308 | 81100118 | 18th January 8110 | 669 |
309 | 81111118 | 18th November 8111 | 3014 |
310 | 81200218 | 18th February 8120 | 669 |
311 | 81211218 | 18th December 8121 | 3012 |
312 | 81300318 | 18th March 8130 | 3684 |
313 | 81400418 | 18th April 8140 | 3682 |
314 | 81500518 | 18th May 8150 | 3684 |
315 | 81600618 | 18th June 8160 | 3682 |
316 | 81700718 | 18th July 8170 | 3684 |
317 | 81800818 | 18th August 8180 | 3683 |
318 | 81900918 | 18th September 8190 | 4057 |
319 | 82011028 | 28th October 8201 | 3014 |
320 | 82100128 | 28th January 8210 | 669 |
321 | 82111128 | 28th November 8211 | 3014 |
322 | 82200228 | 28th February 8220 | 669 |
323 | 82211228 | 28th December 8221 | 3012 |
324 | 82300328 | 28th March 8230 | 3684 |
325 | 82400428 | 28th April 8240 | 3682 |
326 | 82500528 | 28th May 8250 | 3684 |
327 | 82600628 | 28th June 8260 | 3682 |
328 | 82700728 | 28th July 8270 | 3684 |
329 | 82800828 | 28th August 8280 | 3683 |
330 | 82900928 | 28th September 8290 | 259698 |
331 | 90011009 | 9th October 9001 | 3014 |
332 | 90100109 | 9th January 9010 | 669 |
333 | 90111109 | 9th November 9011 | 3014 |
334 | 90200209 | 9th February 9020 | 669 |
335 | 90211209 | 9th December 9021 | 3012 |
336 | 90300309 | 9th March 9030 | 3684 |
337 | 90400409 | 9th April 9040 | 3682 |
338 | 90500509 | 9th May 9050 | 3684 |
339 | 90600609 | 9th June 9060 | 3682 |
340 | 90700709 | 9th July 9070 | 3684 |
341 | 90800809 | 9th August 9080 | 3683 |
342 | 90900909 | 9th September 9090 | 4057 |
343 | 91011019 | 19th October 9101 | 3014 |
344 | 91100119 | 19th January 9110 | 669 |
345 | 91111119 | 19th November 9111 | 3014 |
346 | 91200219 | 19th February 9120 | 669 |
347 | 91211219 | 19th December 9121 | 3012 |
348 | 91300319 | 19th March 9130 | 3684 |
349 | 91400419 | 19th April 9140 | 3682 |
350 | 91500519 | 19th May 9150 | 3684 |
351 | 91600619 | 19th June 9160 | 3682 |
352 | 91700719 | 19th July 9170 | 3684 |
353 | 91800819 | 19th August 9180 | 3683 |
354 | 91900919 | 19th September 9190 | 4058 |
355 | 92011029 | 29th October 9201 | 3014 |
356 | 92100129 | 29th January 9210 | 669 |
357 | 92111129 | 29th November 9211 | 3014 |
358 | 92200229 | 29th February 9220 | 669 |
359 | 92211229 | 29th December 9221 | 3012 |
360 | 92300329 | 29th March 9230 | 3684 |
361 | 92400429 | 29th April 9240 | 3682 |
362 | 92500529 | 29th May 9250 | 3684 |
363 | 92600629 | 29th June 9260 | 3682 |
364 | 92700729 | 29th July 9270 | 3684 |
365 | 92800829 | 29th August 9280 | 3683 |
366 | 92900929 | 29th September 9290 |
Intervals between one palindromic date and the next show some repetition. Here is how frequently different intervals appear:
Interval (days) | Count |
---|---|
669 | 59 |
3012 | 31 |
3014 | 60 |
3682 | 60 |
3683 | 31 |
3684 | 91 |
4057 | 16 |
4058 | 5 |
4352 | 1 |
7366 | 2 |
223164 | 1 |
226847 | 1 |
259698 | 7 |
Total | 365 |
Discussion (16)
2021-12-02 00:45:09 by qntm:
2021-12-02 06:48:31 by hobbs:
2021-12-02 18:04:37 by laverya:
2021-12-02 18:23:38 by SubmanUK:
2021-12-02 21:32:23 by Boter:
2021-12-02 21:45:22 by P:
2021-12-03 05:31:36 by tanamr:
2021-12-08 18:33:56 by mszegedy:
2021-12-08 18:34:17 by mszegedy:
2021-12-17 07:38:37 by Ingvar:
2022-01-14 02:01:13 by wroughage:
2022-01-14 02:03:18 by qntm:
2022-01-21 17:06:47 by MrRandom:
2022-01-22 04:58:09 by David:
2022-03-23 01:53:24 by Soyfish:
2022-05-09 15:35:37 by iewqr: