Primality proof for n = 670261:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=11171.html>11171 is prime.</a>
<br>b^((n-1)/11171)-1 mod n = 201447, which is a unit, inverse 647719.
<p>(11171) divides n-1.
<p>(11171)^2 > n.
<p>n is prime by Pocklington's theorem.