﻿﻿﻿ Every Day Counts

Centred Square Prime Days

Age: 19,810 days
Date of birth
Your 36th Centred Square Prime Day is on
Tuesday
when you will be
20,201 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
27 Jul 2024
19,813
3
54
13 Oct 2024
19,891
81
54
18 Nov 2024
19,927
117
54
28 Nov 2024
19,937
127
54
28 Nov 2024
19,937
127
54
10 Feb 2025
20,011
201
54
19 Aug 2025
20,201
391
55
22 Jan 2026
20,357
547
55
13 Oct 2048
28,657
8,847
78
08 Feb 2078
39,367
19,557
107
10 Jan 2090
43,721
23,911
119
10 Jun 2103
48,619
28,809
133
04 Oct 2149
65,537
45,727
179
17 Nov 2244
100,279
80,469
274
06 Jun 2268
108,881
89,071
298
09 Mar 2329
131,071
111,261
358
01 Jul 7787
2,124,679
2,104,869
5817
Ordinal
Day Age
Date
Age
1st
5
04 May 1970
0
2nd
13
12 May 1970
0
3rd
41
09 Jun 1970
0
4th
61
29 Jun 1970
0
5th
113
20 Aug 1970
0
6th
181
27 Oct 1970
0
7th
313
08 Mar 1971
0
8th
421
24 Jun 1971
1
9th
613
02 Jan 1972
1
10th
761
29 May 1972
2
11th
1,013
05 Feb 1973
2
12th
1,201
12 Aug 1973
3
13th
1,301
20 Nov 1973
3
14th
1,741
03 Feb 1975
4
15th
1,861
03 Jun 1975
5
16th
2,113
10 Feb 1976
5
17th
2,381
04 Nov 1976
6
18th
2,521
24 Mar 1977
6
19th
3,121
14 Nov 1978
8
20th
3,613
20 Mar 1980
9
21st
4,513
06 Sep 1982
12
22nd
5,101
16 Apr 1984
13
23rd
7,321
15 May 1990
20
24th
8,581
26 Oct 1993
23
25th
9,661
10 Oct 1996
26
26th
9,941
17 Jul 1997
27
27th
10,513
09 Feb 1999
28
28th
12,641
07 Dec 2004
34
29th
13,613
06 Aug 2007
37
30th
14,281
04 Jun 2009
39
31st
14,621
10 May 2010
40
32nd
15,313
01 Apr 2012
41
33rd
16,381
05 Mar 2015
44
34th
19,013
19 May 2022
52
35th
19,801
15 Jul 2024
54
36th
20,201
19 Aug 2025
55
1
37th
21,013
09 Nov 2027
57
38th
21,841
14 Feb 2030
59
39th
23,981
25 Dec 2035
65
40th
24,421
09 Mar 2037
66
41st
26,681
17 May 2043
73