Question

How to check whether a number is a perfect number in Python

Answer 1

# If the sum of all factors of a number is equal to the number, then the number is perfect
 
# Factors of a number are numbers that divide the number evenly
    
# 6
# factors = 1, 2, 3
# 1 + 2 + 3 = 6

import math

def is_perfect(n: int) -> bool:
    if n < 2:
        return False

    total = 1
    limit = int(math.sqrt(n))

    for i in range(2, limit + 1):
        if n % i == 0:
            total += i
            pair = n // i
            if pair != i:
                total += pair

    return total == n


def main():
    print("Perfect numbers up to 10,000:")
    for i in range(1, 10001):
        if is_perfect(i):
            print(i)


if __name__ == "__main__":
    main()


"""
run:

Perfect numbers up to 10,000:
6
28
496
8128

"""

 

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