Primality proof for n = 409477:

Take b = 2.

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

34123 is prime.
b^((n-1)/34123)-1 mod n = 4095, which is a unit, inverse 391678.

(34123) divides n-1.

(34123)^2 > n.

n is prime by Pocklington's theorem.