[D66] [JD: 15] Number 23 (Re: Epoch)

[R.O.]

http://math.fau.edu/richman/Interesting/WebSite/Number23.pdf
https://www.quora.com/What-is-mathematically-special-about-the-number-23
https://sites.google.com/site/numberopedia/number23
https://www.independent.co.uk/news/uk/this-britain/23-fascinating-facts-about-number-twenty-three-6262624.html


  John Forbes Nash, the Nobel Prize-winning economist who was the 
subject of the film, A Beautiful Mind, starring Russell Crowe, was 
obsessed with 23. It featured prominently in his battle with mental 
illness. His breakdown began when he claimed that a photograph of Pope 
John XXIII on the cover of Life magazine was in fact him, the proof 
being that 23 was his favourite number. Nash published 23 scientific 
articles.

[...]

The number 23 appears in only one Pythagorean Triple:[23;264;265].

As a sum of three odd primes:23 = 3+3+17 = 3+7+13 = 5+5+13 = 5+7+11.

The 23-digit number 11111111111111111111111 is a prime.  A number whose 
digitsare all 1 is called a repunit.

The number 23 is the only prime p such that p! is p digits long. (Number 
Gossip and Prime Curios)

Indeed,23! = 25 852 016 738 884 976 640 000—count them.

In fact,23 is one of only four numbers n such that n!is n digits long.

The others are 1,22, and24.

The number 23! is the smallest pandigital factorial—it contains each 
digit at least once.(Number Gossip)

The number 23 is the smallest prime that is not a twin prime.