﻿﻿﻿ Every Day Counts

Centred Square Prime Days

Age: 19,813 days
Date of birth
Your 36th Centred Square Prime Day is on
Saturday
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
24 Jul 2024
19,813
today
54
10 Oct 2024
19,891
78
54
15 Nov 2024
19,927
114
54
25 Nov 2024
19,937
124
54
25 Nov 2024
19,937
124
54
07 Feb 2025
20,011
198
54
16 Aug 2025
20,201
388
55
19 Jan 2026
20,357
544
55
10 Oct 2048
28,657
8,844
78
05 Feb 2078
39,367
19,554
107
07 Jan 2090
43,721
23,908
119
07 Jun 2103
48,619
28,806
133
01 Oct 2149
65,537
45,724
179
14 Nov 2244
100,279
80,466
274
03 Jun 2268
108,881
89,068
298
06 Mar 2329
131,071
111,258
358
28 Jun 7787
2,124,679
2,104,866
5817
Ordinal
Day Age
Date
Age
1st
5
01 May 1970
0
2nd
13
09 May 1970
0
3rd
41
06 Jun 1970
0
4th
61
26 Jun 1970
0
5th
113
17 Aug 1970
0
6th
181
24 Oct 1970
0
7th
313
05 Mar 1971
0
8th
421
21 Jun 1971
1
9th
613
30 Dec 1971
1
10th
761
26 May 1972
2
11th
1,013
02 Feb 1973
2
12th
1,201
09 Aug 1973
3
13th
1,301
17 Nov 1973
3
14th
1,741
31 Jan 1975
4
15th
1,861
31 May 1975
5
16th
2,113
07 Feb 1976
5
17th
2,381
01 Nov 1976
6
18th
2,521
21 Mar 1977
6
19th
3,121
11 Nov 1978
8
20th
3,613
17 Mar 1980
9
21st
4,513
03 Sep 1982
12
22nd
5,101
13 Apr 1984
13
23rd
7,321
12 May 1990
20
24th
8,581
23 Oct 1993
23
25th
9,661
07 Oct 1996
26
26th
9,941
14 Jul 1997
27
27th
10,513
06 Feb 1999
28
28th
12,641
04 Dec 2004
34
29th
13,613
03 Aug 2007
37
30th
14,281
01 Jun 2009
39
31st
14,621
07 May 2010
40
32nd
15,313
29 Mar 2012
41
33rd
16,381
02 Mar 2015
44
34th
19,013
16 May 2022
52
35th
19,801
12 Jul 2024
54
36th
20,201
16 Aug 2025
55
1
37th
21,013
06 Nov 2027
57
38th
21,841
11 Feb 2030
59
39th
23,981
22 Dec 2035
65
40th
24,421
06 Mar 2037
66
41st
26,681
14 May 2043
73