Every Day Counts
Centred Square Prime Days
 
Age: 9,656 days
Date of birth
Your 25th Centred Square Prime Day is on
Wednesday
when you will be
9,661 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
15 Jul 2020
9,661
5
26
15 Jul 2020
9,661
5
26
12 Aug 2020
9,689
33
26
13 Sep 2020
9,721
65
26
25 Sep 2020
9,733
77
26
06 Sep 2021
10,079
423
27
13 Mar 2022
10,267
611
28
16 Apr 2022
10,301
645
28
23 Jun 2022
10,369
713
28
10 Oct 2026
11,939
2,283
32
21 Dec 2026
12,011
2,355
32
15 Dec 2032
14,197
4,541
38
29 Mar 2038
16,127
6,471
44
14 Mar 2040
16,843
7,187
46
12 Nov 2043
18,181
8,525
49
18 Jul 2072
28,657
19,001
78
09 Jul 2173
65,537
55,881
179
12 Dec 2352
131,071
121,415
358
Ordinal
Day Age
Date
Age
1st
5
06 Feb 1994
0
2nd
13
14 Feb 1994
0
3rd
41
14 Mar 1994
0
4th
61
03 Apr 1994
0
5th
113
25 May 1994
0
6th
181
01 Aug 1994
0
7th
313
11 Dec 1994
0
8th
421
29 Mar 1995
1
9th
613
07 Oct 1995
1
10th
761
03 Mar 1996
2
11th
1,013
10 Nov 1996
2
12th
1,201
17 May 1997
3
13th
1,301
25 Aug 1997
3
14th
1,741
08 Nov 1998
4
15th
1,861
08 Mar 1999
5
16th
2,113
15 Nov 1999
5
17th
2,381
09 Aug 2000
6
18th
2,521
27 Dec 2000
6
19th
3,121
19 Aug 2002
8
20th
3,613
24 Dec 2003
9
21st
4,513
11 Jun 2006
12
22nd
5,101
20 Jan 2008
13
23rd
7,321
17 Feb 2014
20
24th
8,581
31 Jul 2017
23
25th
9,661
15 Jul 2020
26
1
26th
9,941
21 Apr 2021
27
27th
10,513
14 Nov 2022
28
28th
12,641
11 Sep 2028
34
29th
13,613
11 May 2031
37
30th
14,281
09 Mar 2033
39
31st
14,621
12 Feb 2034
40
32nd
15,313
05 Jan 2036
41
33rd
16,381
08 Dec 2038
44
34th
19,013
21 Feb 2046
52
35th
19,801
19 Apr 2048
54
36th
20,201
24 May 2049
55
37th
21,013
14 Aug 2051
57
38th
21,841
19 Nov 2053
59
39th
23,981
29 Sep 2059
65
40th
24,421
12 Dec 2060
66
41st
26,681
19 Feb 2067
73