perfect_number.py

"""
== Perfect Number ==
In number theory, a perfect number is a positive integer
that is equal to the sum of its positive divisors, excluding
the number itself.
For 6 ==> divisors[1, 2, 3, 6]
Excluding 6 sum(divisors) = 1 + 2 + 3 = 6
So, 6 is a Perfect Number

Other examples of Perfect Numbers: 28, 486, ...

https://en.wikipedia.org/wiki/Perfect_number
"""


def perfect(number: int) -> bool:
    divisors = []
    for i in range(1, ((number // 2) + 1)):
        """
                starting from 1 as division by 0
                will raise error.
                A number at most can be divisible
                by the half of the number except
                the number itself
                6 at most can be divisible by 3
                except 6 itself
        """

        """
                >>> perfect(27)
                False
                >>> perfect(28)
                True
                >>> perfect(29)
                False
        """

        if (number % i) == 0:
            divisors.append(i)

    if sum(divisors) == number:
        return True
    else:
        return False


if __name__ == "__main__":
    print("Program to check whether a number is a Perfect number or not.......")
    number = int(input("Enter number: "))
    print(f"{number} is {'' if perfect(number) else 'not'} a Perfect Number.")