Primality proof for n = 153259:

Take b = 2.

b^(n-1) mod n = 1.

89 is prime.
b^((n-1)/89)-1 mod n = 143377, which is a unit, inverse 100141.

41 is prime.
b^((n-1)/41)-1 mod n = 153016, which is a unit, inverse 138753.

(41 * 89) divides n-1.

(41 * 89)^2 > n.

n is prime by Pocklington's theorem.