Primality proof for n = 196687:
<p>Take b = 3.
<p>b^(n-1) mod n = 1.
<p><a href=223.html>223 is prime.</a>
<br>b^((n-1)/223)-1 mod n = 28615, which is a unit, inverse 598.
<p><a href=7.html>7 is prime.</a>
<br>b^((n-1)/7)-1 mod n = 178871, which is a unit, inverse 14385.
<p>(7^2 * 223) divides n-1.
<p>(7^2 * 223)^2 > n.
<p>n is prime by Pocklington's theorem.