Every Day Counts
Centred Square Prime Days
 
Age: 20,315 days
Date of birth
Your 37th Centred Square Prime Day is on
Wednesday
when you will be
21,013 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
24 Nov 2018
20,323
8
55
28 Dec 2018
20,357
42
55
30 Dec 2018
20,359
44
55
14 Oct 2020
21,013
698
57
02 Sep 2022
21,701
1,386
59
17 Sep 2024
22,447
2,132
61
18 Sep 2041
28,657
8,342
78
03 Sep 2045
30,103
9,788
82
06 Feb 2065
37,199
16,884
101
14 Jan 2071
39,367
19,052
107
16 Dec 2082
43,721
23,406
119
14 May 2096
48,619
28,304
133
09 Sep 2142
65,537
45,222
179
23 Oct 2237
100,279
79,964
274
12 May 2261
108,881
88,566
298
12 Feb 2322
131,071
110,756
358
05 Jun 7780
2,124,679
2,104,364
5817
Ordinal
Day Age
Date
Age
1st
5
09 Apr 1963
0
2nd
13
17 Apr 1963
0
3rd
41
15 May 1963
0
4th
61
04 Jun 1963
0
5th
113
26 Jul 1963
0
6th
181
02 Oct 1963
0
7th
313
11 Feb 1964
0
8th
421
29 May 1964
1
9th
613
07 Dec 1964
1
10th
761
04 May 1965
2
11th
1,013
11 Jan 1966
2
12th
1,201
18 Jul 1966
3
13th
1,301
26 Oct 1966
3
14th
1,741
09 Jan 1968
4
15th
1,861
08 May 1968
5
16th
2,113
15 Jan 1969
5
17th
2,381
10 Oct 1969
6
18th
2,521
27 Feb 1970
6
19th
3,121
20 Oct 1971
8
20th
3,613
23 Feb 1973
9
21st
4,513
12 Aug 1975
12
22nd
5,101
22 Mar 1977
13
23rd
7,321
20 Apr 1983
20
24th
8,581
01 Oct 1986
23
25th
9,661
15 Sep 1989
26
26th
9,941
22 Jun 1990
27
27th
10,513
15 Jan 1992
28
28th
12,641
12 Nov 1997
34
29th
13,613
11 Jul 2000
37
30th
14,281
10 May 2002
39
31st
14,621
15 Apr 2003
40
32nd
15,313
07 Mar 2005
41
33rd
16,381
08 Feb 2008
44
34th
19,013
24 Apr 2015
52
35th
19,801
20 Jun 2017
54
36th
20,201
25 Jul 2018
55
37th
21,013
14 Oct 2020
57
1
38th
21,841
20 Jan 2023
59
39th
23,981
29 Nov 2028
65
40th
24,421
12 Feb 2030
66
41st
26,681
21 Apr 2036
73