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.