A prime number is always greater then1. True or false and why?

Answer 1

True. It is because that is how prime numbers are defined. If 1 or negative integers were included in the definition then The Fundamental Theorem of Arithmetic* would fail. That would have serious consequences for many other theorems.

In simple terms, The Fundamental Theorem of Arithmetic states that for any positive integer greater than 1, there is only one prime factorisation if you disregard the order in which the factors are written.,