<![CDATA[Fun math fact: 19937 is prime even when you take the end digit and put it back at the start repeatedly.]]>Fun math fact: 19937 is prime even when you take the end digit and put it back at the start repeatedly. It's known as a circular prime:

19937 = prime
71993 = prime
37199 = prime
93719 = prime
99371 = prime

It's also one of the 52 known Mersenne prime p-values (2^p-1), as 2^19937-1 is prime, and this Mersenne prime is the most common used period length for the Mersenne Twister pseudorandom number generator.

]]>https://board.circlewithadot.net/topic/f836f696-05cd-451a-a9cc-6157b2e13f3c/fun-math-fact-19937-is-prime-even-when-you-take-the-end-digit-and-put-it-back-at-the-start-repeatedly.RSS for NodeMon, 06 Apr 2026 06:37:01 GMTSun, 29 Mar 2026 23:35:58 GMT60