Primality proof for n = 1866961:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=2593.html>2593 is prime.</a>
<br>b^((n-1)/2593)-1 mod n = 1566413, which is a unit, inverse 176249.
<p>(2593) divides n-1.
<p>(2593)^2 > n.
<p>n is prime by Pocklington's theorem.