A program to determine if a number is a perfect number.

perfect-number.py

"""
A program to determine if a number is a perfect number.
"""


def is_perfect_number(n):
    """Determines if a given number is a perfect number.

    Any number can be perfect number, if the sum of its
    positive divisors excluding the number itself is equal
    to that number.

    For example, 6 is a perfect number because 6 is divisible
    by 1, 2, 3 and 6. So, the sum of these values are: 1+2+3 = 6.
    
    === Parameters ===
    n: int
        The number to we want to determine if it's
        a perfect number or not.
    
    === Return ===
    bool: True|False
        If the number is a perfect number, it returns
        True otherwise we return False.
    """
    # Initial value of total
    total = 0
    
    for i in range(1, n):
        # Add the sum of n's multiple or the sum of
        # numbers that are "perfectly divisible by i".
        if n % i == 0:
            # Add the multiple to total.
            total += i
        
        # Don't search further if the sum > number.
        if total > n:
            break
    
    # Logic: `sum == number ? perfect : imperfect`.
    return True if total == n else False


def main():
    # We're dealing with postive integers here...
    number = abs(int(input('Enter a +ve integer: ')))

    # Call the function to determine if `number` is a
    # perfect number.
    ans = is_perfect_number(number)

    # Log appropriate message to the output stream.
    if ans:
        print('{} is a perfect number!'.format(number))
    else:
        print('{} is not a perfect number!'.format(number))


if __name__ == '__main__':
    main()