﻿﻿﻿ Every Day Counts

Centred Square Prime Days

Age: 13,619 days
Date of birth
Your 30th Centred Square Prime Day is on
Friday
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
04 Dec 2023
13,619
today
37
23 Jan 2024
13,669
50
37
02 Feb 2024
13,679
60
37
04 Feb 2024
13,681
62
37
03 Jul 2024
13,831
212
37
04 Jul 2025
14,197
578
38
26 Sep 2025
14,281
662
39
22 May 2026
14,519
900
39
16 Oct 2030
16,127
2,508
44
01 Oct 2032
16,843
3,224
46
17 Jul 2034
17,497
3,878
47
31 May 2036
18,181
4,562
49
23 Sep 2039
19,391
5,772
53
22 Mar 2041
19,937
6,318
54
04 Feb 2065
28,657
15,038
78
02 Oct 2119
48,619
35,000
133
26 Jan 2166
65,537
51,918
179
01 Jul 2345
131,071
117,452
358
Ordinal
Day Age
Date
Age
1st
5
26 Aug 1986
0
2nd
13
03 Sep 1986
0
3rd
41
01 Oct 1986
0
4th
61
21 Oct 1986
0
5th
113
12 Dec 1986
0
6th
181
18 Feb 1987
0
7th
313
30 Jun 1987
0
8th
421
16 Oct 1987
1
9th
613
25 Apr 1988
1
10th
761
20 Sep 1988
2
11th
1,013
30 May 1989
2
12th
1,201
04 Dec 1989
3
13th
1,301
14 Mar 1990
3
14th
1,741
28 May 1991
4
15th
1,861
25 Sep 1991
5
16th
2,113
03 Jun 1992
5
17th
2,381
26 Feb 1993
6
18th
2,521
16 Jul 1993
6
19th
3,121
08 Mar 1995
8
20th
3,613
12 Jul 1996
9
21st
4,513
29 Dec 1998
12
22nd
5,101
08 Aug 2000
13
23rd
7,321
06 Sep 2006
20
24th
8,581
17 Feb 2010
23
25th
9,661
01 Feb 2013
26
26th
9,941
08 Nov 2013
27
27th
10,513
03 Jun 2015
28
28th
12,641
31 Mar 2021
34
29th
13,613
28 Nov 2023
37
30th
14,281
26 Sep 2025
39
1
31st
14,621
01 Sep 2026
40
32nd
15,313
24 Jul 2028
41
33rd
16,381
27 Jun 2031
44
34th
19,013
10 Sep 2038
52
35th
19,801
06 Nov 2040
54
36th
20,201
11 Dec 2041
55
37th
21,013
02 Mar 2044
57
38th
21,841
08 Jun 2046
59
39th
23,981
17 Apr 2052
65
40th
24,421
01 Jul 2053
66
41st
26,681
08 Sep 2059
73