The value of Euler's Totient function φ(77) is :

The correct answer is Option (3) → 60

Euler's Totient function,

$\phi(n)=n\underset{p|n}{∏}\left(1-\frac{1}{p}\right)$

$\phi(77)=77×\left(1-\frac{1}{7}\right)×\left(1-\frac{1}{11}\right)$  $77=7×11$

$=77×\frac{6}{7}×\frac{10}{11}=60$