Is $7\times11\times13+13$ a composite number? Justify your answer.

Given: $7\times11\times13+13$ 

To do: To find weather the given number is composite? and To justify.

As given $7\times11\times13+13$

$=13\times(7\times11+1)=13\times78$ 

This number is multiple of two integers. Hence it has more than two factors. Hence it is a composite number.