﻿﻿﻿ Every Day Counts

Centred Square Prime Days

Age: 12,642 days
Date of birth
Your 29th Centred Square Prime Day is on
Monday
when you will be
13,613 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
29 Jul 2024
12,647
5
34
11 Oct 2024
12,721
79
34
10 Apr 2026
13,267
625
36
28 Nov 2026
13,499
857
36
22 Mar 2027
13,613
971
37
27 May 2027
13,679
1,037
37
29 May 2027
13,681
1,039
37
26 Oct 2028
14,197
1,555
38
07 Feb 2034
16,127
3,485
44
24 Jan 2036
16,843
4,201
46
08 Nov 2037
17,497
4,855
47
23 Sep 2039
18,181
5,539
49
15 Jan 2043
19,391
6,749
53
14 Jul 2044
19,937
7,295
54
29 May 2068
28,657
16,015
78
24 Jan 2123
48,619
35,977
133
20 May 2169
65,537
52,895
179
23 Oct 2348
131,071
118,429
358
Ordinal
Day Age
Date
Age
1st
5
18 Dec 1989
0
2nd
13
26 Dec 1989
0
3rd
41
23 Jan 1990
0
4th
61
12 Feb 1990
0
5th
113
05 Apr 1990
0
6th
181
12 Jun 1990
0
7th
313
22 Oct 1990
0
8th
421
07 Feb 1991
1
9th
613
18 Aug 1991
1
10th
761
13 Jan 1992
2
11th
1,013
21 Sep 1992
2
12th
1,201
28 Mar 1993
3
13th
1,301
06 Jul 1993
3
14th
1,741
19 Sep 1994
4
15th
1,861
17 Jan 1995
5
16th
2,113
26 Sep 1995
5
17th
2,381
20 Jun 1996
6
18th
2,521
07 Nov 1996
6
19th
3,121
30 Jun 1998
8
20th
3,613
04 Nov 1999
9
21st
4,513
22 Apr 2002
12
22nd
5,101
01 Dec 2003
13
23rd
7,321
29 Dec 2009
20
24th
8,581
11 Jun 2013
23
25th
9,661
26 May 2016
26
26th
9,941
02 Mar 2017
27
27th
10,513
25 Sep 2018
28
28th
12,641
23 Jul 2024
34
29th
13,613
22 Mar 2027
37
1
30th
14,281
18 Jan 2029
39
31st
14,621
24 Dec 2029
40
32nd
15,313
16 Nov 2031
41
33rd
16,381
19 Oct 2034
44
34th
19,013
02 Jan 2042
52
35th
19,801
29 Feb 2044
54
36th
20,201
04 Apr 2045
55
37th
21,013
25 Jun 2047
57
38th
21,841
30 Sep 2049
59
39th
23,981
10 Aug 2055
65
40th
24,421
23 Oct 2056
66
41st
26,681
31 Dec 2062
73