﻿﻿﻿ Every Day Counts

Centred Square Prime Days

Age: 24,441 days
Date of birth
Your 41st Centred Square Prime Day is on
Wednesday
when you will be
26,681 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
26 Jul 2024
24,443
2
66
01 Dec 2024
24,571
130
67
01 Mar 2027
25,391
950
69
30 Aug 2028
25,939
1,498
71
11 Sep 2030
26,681
2,240
73
08 Feb 2036
28,657
4,216
78
24 Jan 2040
30,103
5,662
82
29 Jun 2059
37,199
12,758
101
05 Jun 2065
39,367
14,926
107
07 May 2077
43,721
19,280
119
22 Jun 2079
44,497
20,056
121
04 Oct 2090
48,619
24,178
133
29 Jan 2137
65,537
41,096
179
14 Mar 2232
100,279
75,838
274
02 Oct 2255
108,881
84,440
298
04 Jul 2316
131,071
106,630
358
26 Oct 7774
2,124,679
2,100,238
5817
Ordinal
Day Age
Date
Age
1st
5
29 Aug 1957
0
2nd
13
06 Sep 1957
0
3rd
41
04 Oct 1957
0
4th
61
24 Oct 1957
0
5th
113
15 Dec 1957
0
6th
181
21 Feb 1958
0
7th
313
03 Jul 1958
0
8th
421
19 Oct 1958
1
9th
613
29 Apr 1959
1
10th
761
24 Sep 1959
2
11th
1,013
02 Jun 1960
2
12th
1,201
07 Dec 1960
3
13th
1,301
17 Mar 1961
3
14th
1,741
31 May 1962
4
15th
1,861
28 Sep 1962
5
16th
2,113
07 Jun 1963
5
17th
2,381
01 Mar 1964
6
18th
2,521
19 Jul 1964
6
19th
3,121
11 Mar 1966
8
20th
3,613
16 Jul 1967
9
21st
4,513
01 Jan 1970
12
22nd
5,101
12 Aug 1971
13
23rd
7,321
09 Sep 1977
20
24th
8,581
20 Feb 1981
23
25th
9,661
05 Feb 1984
26
26th
9,941
11 Nov 1984
27
27th
10,513
06 Jun 1986
28
28th
12,641
03 Apr 1992
34
29th
13,613
01 Dec 1994
37
30th
14,281
29 Sep 1996
39
31st
14,621
04 Sep 1997
40
32nd
15,313
28 Jul 1999
41
33rd
16,381
30 Jun 2002
44
34th
19,013
13 Sep 2009
52
35th
19,801
10 Nov 2011
54
36th
20,201
14 Dec 2012
55
37th
21,013
06 Mar 2015
57
38th
21,841
11 Jun 2017
59
39th
23,981
21 Apr 2023
65
40th
24,421
04 Jul 2024
66
41st
26,681
11 Sep 2030
73
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