Prove that a positive integer n is prime number, if no prime p less than or equal to `sqrtn` divides n.

Explanation

Let the `n` be a positive integer such that no. prime less than `sqrt(n)` divides `n`. Then , we will prove that `n` is prime. Suppose `n` is not a prime. Then, We may write


`n=ab` where `1 < ` `a<=b`


`a<=sqrt(n)` and `b>=sqrt(n)`


Let `p` be a prime factor of `a`. Then `p<=a<=sqrt(n)` and `p | a`


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