Introduction

The task is to find largest prime factor of a given positive integer.

Program

import math 
def find(ip_int): 
    large_prime = -1
    ip_int = int(ip_int)
# Find total number of 2’s dividing the number
    while ip_int % 2 == 0: 
        large_prime = 2
        ip_int /= 2  
# Find all prime numbers 
    for num in range(3, int(math.sqrt(ip_int)) + 1, 2): 
        while ip_int % num == 0: 
            large_prime= num 
            ip_int = ip_int / num 
    if ip_int > 2: 
        large_prime = ip_int 
    return int(large_prime) 
ip_int = input("Enter the positive integer: ")
print("The largest prime factor is: ", find(ip_int))

Output:

Explanation

In the code, we have found all the prime factors of the number 42 i.e. 2 * 3 * 7 and returned the largest number.