Primality proof for n = 6719:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=3359.html>3359 is prime.</a>
<br>b^((n-1)/3359)-1 mod n = 3, which is a unit, inverse 2240.
<p>(3359) divides n-1.
<p>(3359)^2 > n.
<p>n is prime by Pocklington's theorem.