﻿﻿﻿ Every Day Counts

Centred Square Prime Days

Age: 14,280 days
Date of birth
Your 30th Centred Square Prime Day is on
Sunday
when you will be
14,281 days old

A centred square prime is a centred square number that is prime.

Unlike regular square numbers, which are never prime, quite a few of the centred square numbers are prime.

Centred square numbers are of the form n2 + (n - 1)2

In elementary number theory, a centred square number is a centred figurate number that gives the number of dots in a square with a dot in the centre and all other dots surrounding the centre dot in successive square layers. That is, each centred square number equals the number of dots within a given city block distance of the centre dot on a regular square lattice. While centred square numbers, like figurate numbers in general, have few if any direct practical applications, they are sometimes studied in recreational mathematics for their elegant geometric and arithmetic properties.

The figures for the first four centred square numbers are shown below:

Next Prime Events
Day Age
Event
Year Age
01 Nov 2020
14,281
tomorrow
39
01 Nov 2020
14,281
tomorrow
39
31 Dec 2020
14,341
61
39
27 Jun 2021
14,519
239
39
25 May 2022
14,851
571
40
21 Nov 2025
16,127
1,847
44
29 Apr 2027
16,651
2,371
45
07 Nov 2027
16,843
2,563
46
22 Aug 2029
17,497
3,217
47
07 Jul 2031
18,181
3,901
49
29 Oct 2034
19,391
5,111
53
27 Apr 2036
19,937
5,657
54
12 Mar 2060
28,657
14,377
78
10 Jun 2101
43,721
29,441
119
07 Nov 2114
48,619
34,339
133
03 Mar 2161
65,537
51,257
179
16 Apr 2256
100,279
85,999
274
06 Aug 2340
131,071
116,791
358
Ordinal
Day Age
Date
Age
1st
5
01 Oct 1981
0
2nd
13
09 Oct 1981
0
3rd
41
06 Nov 1981
0
4th
61
26 Nov 1981
0
5th
113
17 Jan 1982
0
6th
181
26 Mar 1982
0
7th
313
05 Aug 1982
0
8th
421
21 Nov 1982
1
9th
613
01 Jun 1983
1
10th
761
27 Oct 1983
2
11th
1,013
05 Jul 1984
2
12th
1,201
09 Jan 1985
3
13th
1,301
19 Apr 1985
3
14th
1,741
03 Jul 1986
4
15th
1,861
31 Oct 1986
5
16th
2,113
10 Jul 1987
5
17th
2,381
03 Apr 1988
6
18th
2,521
21 Aug 1988
6
19th
3,121
13 Apr 1990
8
20th
3,613
18 Aug 1991
9
21st
4,513
03 Feb 1994
12
22nd
5,101
14 Sep 1995
13
23rd
7,321
12 Oct 2001
20
24th
8,581
25 Mar 2005
23
25th
9,661
09 Mar 2008
26
26th
9,941
14 Dec 2008
27
27th
10,513
09 Jul 2010
28
28th
12,641
06 May 2016
34
29th
13,613
03 Jan 2019
37
30th
14,281
01 Nov 2020
39
1
31st
14,621
07 Oct 2021
40
32nd
15,313
30 Aug 2023
41
33rd
16,381
02 Aug 2026
44
34th
19,013
16 Oct 2033
52
35th
19,801
13 Dec 2035
54
36th
20,201
16 Jan 2037
55
37th
21,013
08 Apr 2039
57
38th
21,841
14 Jul 2041
59
39th
23,981
24 May 2047
65
40th
24,421
06 Aug 2048
66
41st
26,681
14 Oct 2054
73