Primality proof for n = 23189:
Take b = 2.
b^(n-1) mod n = 1.
31 is prime.
b^((n-1)/31)-1 mod n = 20539, which is a unit, inverse 19330.
17 is prime.
b^((n-1)/17)-1 mod n = 6134, which is a unit, inverse 12154.
(17 * 31) divides n-1.
(17 * 31)^2 > n.
n is prime by Pocklington's theorem.