# Math Help - Euler's Totient Function

1. ## Euler's Totient Function

Hi, I was just wondering if someone could confirm that the following is correct? Just a yes or no would suffice.

$\varphi (190) = 72$

Thanks

2. Yes it looks correct, since

$\varphi(p^k)=(p-1)p^{k-1}$ for a prime p and using the fact that phi is multiplicative i.e
$\varphi(ab)= \varphi(a) * \varphi(b)$

Then

$
\varphi (190) = 72
$

$

\varphi(190)=\varphi(2*19*5)=\varphi(2) * \varphi(5) * \varphi(19)
$

$
=1(2^{1-1}) *4(5^{1-1}) *18(19^{1-1}) \ { }= (2^0)*4(5^0)*18(19^0) = 4*18=72
$