Primality proof for n = 880691887:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=16309109.html>16309109 is prime.</a>
<br>b^((n-1)/16309109)-1 mod n = 81977208, which is a unit, inverse 233990991.
<p>(16309109) divides n-1.
<p>(16309109)^2 > n.
<p>n is prime by Pocklington's theorem.