Primality proof for n = 1553407:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=2909.html>2909 is prime.</a>
<br>b^((n-1)/2909)-1 mod n = 1312388, which is a unit, inverse 1538480.
<p>(2909) divides n-1.
<p>(2909)^2 > n.
<p>n is prime by Pocklington's theorem.