Primality proof for n = 290923:

Take b = 2.

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

48487 is prime.
b^((n-1)/48487)-1 mod n = 63, which is a unit, inverse 106210.

(48487) divides n-1.

(48487)^2 > n.

n is prime by Pocklington's theorem.