Primality proof for n = 275027:
Take b = 2.
b^(n-1) mod n = 1.
8089 is prime. b^((n-1)/8089)-1 mod n = 32601, which is a unit, inverse 230037.
(8089) divides n-1.
(8089)^2 > n.
n is prime by Pocklington's theorem.