Primality proof for n = 6720124867:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=7537.html>7537 is prime.</a>
<br>b^((n-1)/7537)-1 mod n = 2154371083, which is a unit, inverse 2314953447.
<p><a href=71.html>71 is prime.</a>
<br>b^((n-1)/71)-1 mod n = 800144366, which is a unit, inverse 489940597.
<p>(71 * 7537) divides n-1.
<p>(71 * 7537)^2 > n.
<p>n is prime by Pocklington's theorem.