Is the number $4^{9}+6^{10}+3^{20}$ prime?

#
This number is a perfect square.

## Solution

$4^{9}+6^{10}+3^{20}=\left(2^{9}\right)^{2}+2 \cdot 2^{9} \cdot 3^{10}+\left(3^{10}\right)^{2}=\left(2^{9}+3^{10}\right)^{2}$.

## Answer

It is not.