So, basically there are two types of numbers i.e., prime numbers and composite numbers.
Understanding that,
Prime numbers are those numbers having 1 and the number itself as factors. And,
Composite numbers are those numbers having factors other than 1 and itself.
It’s seen that,
3 × 5 × 7+ 7 = 7 × (3 × 5 + 1) = 7 × (15 + 1) = 7 × 16
Since, the given expression has 7 and 16 as its factors we can conclude that it is a composite number.
