﻿﻿﻿ Every Day Counts

Centred Square Prime Days

Age: 21,024 days
Date of birth
Your 38th Centred Square Prime Day is on
Monday
when you will be
21,841 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
30 Oct 2019
21,031
7
57
16 Oct 2020
21,383
359
58
30 Aug 2021
21,701
677
59
17 Jan 2022
21,841
817
59
15 Sep 2023
22,447
1,423
61
27 Nov 2025
23,251
2,227
63
15 Sep 2040
28,657
7,633
78
31 Aug 2044
30,103
9,079
82
04 Feb 2064
37,199
16,175
101
11 Jan 2070
39,367
18,343
107
13 Dec 2081
43,721
22,697
119
12 May 2095
48,619
27,595
133
06 Sep 2141
65,537
44,513
179
20 Oct 2236
100,279
79,255
274
09 May 2260
108,881
87,857
298
09 Feb 2321
131,071
110,047
358
03 Jun 7779
2,124,679
2,103,655
5817
Ordinal
Day Age
Date
Age
1st
5
06 Apr 1962
0
2nd
13
14 Apr 1962
0
3rd
41
12 May 1962
0
4th
61
01 Jun 1962
0
5th
113
23 Jul 1962
0
6th
181
29 Sep 1962
0
7th
313
08 Feb 1963
0
8th
421
27 May 1963
1
9th
613
05 Dec 1963
1
10th
761
01 May 1964
2
11th
1,013
08 Jan 1965
2
12th
1,201
15 Jul 1965
3
13th
1,301
23 Oct 1965
3
14th
1,741
06 Jan 1967
4
15th
1,861
06 May 1967
5
16th
2,113
13 Jan 1968
5
17th
2,381
07 Oct 1968
6
18th
2,521
24 Feb 1969
6
19th
3,121
17 Oct 1970
8
20th
3,613
21 Feb 1972
9
21st
4,513
09 Aug 1974
12
22nd
5,101
19 Mar 1976
13
23rd
7,321
17 Apr 1982
20
24th
8,581
28 Sep 1985
23
25th
9,661
12 Sep 1988
26
26th
9,941
19 Jun 1989
27
27th
10,513
12 Jan 1991
28
28th
12,641
09 Nov 1996
34
29th
13,613
09 Jul 1999
37
30th
14,281
07 May 2001
39
31st
14,621
12 Apr 2002
40
32nd
15,313
04 Mar 2004
41
33rd
16,381
05 Feb 2007
44
34th
19,013
21 Apr 2014
52
35th
19,801
17 Jun 2016
54
36th
20,201
22 Jul 2017
55
37th
21,013
12 Oct 2019
57
38th
21,841
17 Jan 2022
59
1
39th
23,981
27 Nov 2027
65
40th
24,421
09 Feb 2029
66
41st
26,681
19 Apr 2035
73