Question 6
Consider all functions $f$ from the set $\mathbb N$ of positive integers into itself satisfying
$$f(n^2f(m))=mf(n)^2$$
for all $m,n\in\mathbb N$. Determine the least possible value of $f(1998)$.
$$f(n^2f(m))=mf(n)^2$$
for all $m,n\in\mathbb N$. Determine the least possible value of $f(1998)$.