Calculate $\displaystyle \varphi (n)$ for $\displaystyle n = 21^{21} $ and $\displaystyle n=2009 $ In each case, express the answer as the product of prime numbers

Let a,b be natural numbers. Show that if $\displaystyle a|b $ then $\displaystyle \varphi (a)| \varphi (b) $

thanks