This algorithm checks that a given positive integer number is prime or not. If it is, then returns a $\mathtt{True}$, otherwise $\mathtt{False}$.

#!/usr/bin/python
 
import math
 
def is_prime(a):
    n = math.sqrt(a)
 
    for i in range(2, int(n)):
        if (a % i) == 0:
            return False
 
    return True

Example:

print(is_prime(127493299))

gives $\mathtt{True}$.

print(is_prime(127493285))

gives $\mathtt{False}$.