Check if the number $3^{2015} - 2^{2015}$ is prime

Question

Is $3^{2015} - 2^{2015}$ a prime. If not, why?

Answer 1

Hint: If $a \mid b$ then $x^a - y^a \mid x^b - y^b$.

Answer 2

HINT: use $$a^5-b^5=(a-b) \left(a^4+a^3 b+a^2 b^2+a b^3+b^4\right)$$ with $a=3^{403}$ and $b=2^{403}$