Primality proof for n = 3617872258517821:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=61292713.html>61292713 is prime.</a>
<br>b^((n-1)/61292713)-1 mod n = 3536708525250730, which is a unit, inverse 1111407430832800.
<p>(61292713) divides n-1.
<p>(61292713)^2 > n.
<p>n is prime by Pocklington's theorem.