Primality proof for n = 1687658803:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=281276467.html>281276467 is prime.</a>
<br>b^((n-1)/281276467)-1 mod n = 63, which is a unit, inverse 857223519.
<p>(281276467) divides n-1.
<p>(281276467)^2 > n.
<p>n is prime by Pocklington's theorem.