1. ## Phi function

Let p and q be distinct primes and m,n integers.

What relationships hold for

phi(p^m*q^n)

2. I assume phi is the Euler totient function.
For any integers m and n, $\displaystyle \phi(m\cdot n)=\phi(m)\cdot \phi(n)$
For any power of a prime p, $\displaystyle \phi(p^k)=p^{k-1}(p-1)$

Think you can take it from there?