Every Day Counts
Centred Square Prime Days
 
Age: 14,661 days
Date of birth
Your 32nd Centred Square Prime Day is on
Saturday
when you will be
15,313 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:

Remind me, please


Next Prime Events
Day Age
Event
Days Ahead
Year Age
03 Jul 2021
14,669
8
40
13 Sep 2021
14,741
80
40
01 Jan 2022
14,851
190
40
08 Apr 2023
15,313
652
41
05 Jul 2023
15,401
740
42
30 Jun 2025
16,127
1,466
44
06 Dec 2026
16,651
1,990
45
16 Jun 2027
16,843
2,182
46
31 Mar 2029
17,497
2,836
47
13 Feb 2031
18,181
3,520
49
07 Jun 2034
19,391
4,730
53
05 Dec 2035
19,937
5,276
54
20 Oct 2059
28,657
13,996
78
17 Jan 2101
43,721
29,060
119
16 Jun 2114
48,619
33,958
133
10 Oct 2160
65,537
50,876
179
24 Nov 2255
100,279
85,618
274
15 Mar 2340
131,071
116,410
358
Ordinal
Day Age
Date
Age
1st
5
10 May 1981
0
2nd
13
18 May 1981
0
3rd
41
15 Jun 1981
0
4th
61
05 Jul 1981
0
5th
113
26 Aug 1981
0
6th
181
02 Nov 1981
0
7th
313
14 Mar 1982
0
8th
421
30 Jun 1982
1
9th
613
08 Jan 1983
1
10th
761
05 Jun 1983
2
11th
1,013
12 Feb 1984
2
12th
1,201
18 Aug 1984
3
13th
1,301
26 Nov 1984
3
14th
1,741
09 Feb 1986
4
15th
1,861
09 Jun 1986
5
16th
2,113
16 Feb 1987
5
17th
2,381
11 Nov 1987
6
18th
2,521
30 Mar 1988
6
19th
3,121
20 Nov 1989
8
20th
3,613
27 Mar 1991
9
21st
4,513
12 Sep 1993
12
22nd
5,101
23 Apr 1995
13
23rd
7,321
21 May 2001
20
24th
8,581
01 Nov 2004
23
25th
9,661
17 Oct 2007
26
26th
9,941
23 Jul 2008
27
27th
10,513
15 Feb 2010
28
28th
12,641
14 Dec 2015
34
29th
13,613
12 Aug 2018
37
30th
14,281
10 Jun 2020
39
31st
14,621
16 May 2021
40
32nd
15,313
08 Apr 2023
41
1
33rd
16,381
11 Mar 2026
44
34th
19,013
25 May 2033
52
35th
19,801
22 Jul 2035
54
36th
20,201
25 Aug 2036
55
37th
21,013
15 Nov 2038
57
38th
21,841
20 Feb 2041
59
39th
23,981
31 Dec 2046
65
40th
24,421
15 Mar 2048
66
41st
26,681
23 May 2054
73