Primality proof for n = 10019573:
Take b = 2.
b^(n-1) mod n = 1.
80803 is prime. b^((n-1)/80803)-1 mod n = 2007763, which is a unit, inverse 1014871.
(80803) divides n-1.
(80803)^2 > n.
n is prime by Pocklington's theorem.