Is there any way to find a number N if it's Carmichael function is given. I know to find the Carmichael function [ C() ] of a given no. But I want to know if there is any method or shortcut to find a number N if it's C() is given.
PARI/GP examples:

n-Carmichael &lt;=> B(n)=eulerphi(n), 

where B(n)=PRODUCT(p: p-1|n-1, where p|n and p-Prime)

It's analog for:
 n-Prime&lt;=> n-1=eulerphi(n)

Your method:
  n-Carmichael &lt;=> C(n)|n-1

where:
  C(n)=znstar(n)[2][1]
PARI/GP examples:

n-Carmichael &lt;=> B(n)=eulerphi(n), 

where B(n)=PRODUCT(p: p-1|n-1, where p|n and p-Prime)

It's analog for:
 n-Prime&lt;=> n-1=eulerphi(n)

Your method:
  n-Carmichael &lt;=> C(n)|n-1

where:
  C(n)=znstar(n)[2][1]