How to justify $\phi(n) \ge \sqrt{n}$

If $\phi(n)$ is the Euler-totient function, how can I show that $\phi(n) \ge \sqrt{n}$?

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$\varphi(2)=1<\sqrt2$. –  Brian M. Scott Feb 20 '13 at 2:00
I'm sure this question has been asked, and answered, here, but I'm not sure how to find it. –  Gerry Myerson Feb 20 '13 at 2:01
$\varphi(6) = 2 < \sqrt{6}$ –  mixedmath Feb 20 '13 at 2:01
See, for example, math.stackexchange.com/questions/301837/… --- especially Brian's answer. –  Gerry Myerson Feb 20 '13 at 2:08
–  Will Jagy Feb 20 '13 at 2:08

Hint: both $\phi(n)$ and $\sqrt{n}$ are multiplicative, so it suffices to consider prime powers.