Primality proof for n = 6945557:

Take b = 2.

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

1736389 is prime.
b^((n-1)/1736389)-1 mod n = 15, which is a unit, inverse 3241260.

(1736389) divides n-1.

(1736389)^2 > n.

n is prime by Pocklington's theorem.