Every Day Counts
Centred Square Prime Days
 
Age: 13,879 days
Date of birth
Your 30th Centred Square Prime Day is on
Wednesday
when you will be
14,281 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
21 Oct 2018
13,879
today
38
12 Dec 2018
13,931
52
38
04 Sep 2019
14,197
318
38
27 Nov 2019
14,281
402
39
22 Jul 2020
14,519
640
39
19 Jun 2021
14,851
972
40
16 Dec 2024
16,127
2,248
44
24 May 2026
16,651
2,772
45
02 Dec 2026
16,843
2,964
46
16 Sep 2028
17,497
3,618
47
01 Aug 2030
18,181
4,302
49
23 Nov 2033
19,391
5,512
53
23 May 2035
19,937
6,058
54
07 Apr 2059
28,657
14,778
78
02 Dec 2113
48,619
34,740
133
28 Mar 2160
65,537
51,658
179
12 May 2255
100,279
86,400
274
01 Sep 2339
131,071
117,192
358
Ordinal
Day Age
Date
Age
1st
5
26 Oct 1980
0
2nd
13
03 Nov 1980
0
3rd
41
01 Dec 1980
0
4th
61
21 Dec 1980
0
5th
113
11 Feb 1981
0
6th
181
20 Apr 1981
0
7th
313
30 Aug 1981
0
8th
421
16 Dec 1981
1
9th
613
26 Jun 1982
1
10th
761
21 Nov 1982
2
11th
1,013
31 Jul 1983
2
12th
1,201
04 Feb 1984
3
13th
1,301
14 May 1984
3
14th
1,741
28 Jul 1985
4
15th
1,861
25 Nov 1985
5
16th
2,113
04 Aug 1986
5
17th
2,381
29 Apr 1987
6
18th
2,521
16 Sep 1987
6
19th
3,121
08 May 1989
8
20th
3,613
12 Sep 1990
9
21st
4,513
28 Feb 1993
12
22nd
5,101
09 Oct 1994
13
23rd
7,321
06 Nov 2000
20
24th
8,581
19 Apr 2004
23
25th
9,661
04 Apr 2007
26
26th
9,941
09 Jan 2008
27
27th
10,513
03 Aug 2009
28
28th
12,641
01 Jun 2015
34
29th
13,613
28 Jan 2018
37
30th
14,281
27 Nov 2019
39
1
31st
14,621
01 Nov 2020
40
32nd
15,313
24 Sep 2022
41
33rd
16,381
27 Aug 2025
44
34th
19,013
10 Nov 2032
52
35th
19,801
07 Jan 2035
54
36th
20,201
11 Feb 2036
55
37th
21,013
03 May 2038
57
38th
21,841
08 Aug 2040
59
39th
23,981
18 Jun 2046
65
40th
24,421
01 Sep 2047
66
41st
26,681
08 Nov 2053
73