If $\phi(n)$ represents Euler's totient function then $\phi(432)$ is:

144

The correct answer is Option (1) → 144

$432 = 2^4 \cdot 3^3$

$\phi(n) = n\left(1-\frac{1}{p_1}\right)\left(1-\frac{1}{p_2}\right)$

$\phi(432) = 432\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)$

$= 432 \cdot \frac{1}{2} \cdot \frac{2}{3}$

$= 432 \cdot \frac{1}{3} = 144$

$\phi(432) = 144$