#### Perfect Number

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```"""
== 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 example: 6 ==> divisors[1, 2, 3, 6]
Excluding 6, the sum(divisors) is 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:
"""
Check if a number is a perfect number.

A perfect number is a positive integer that is equal to the sum of its proper
divisors (excluding itself).

Args:
number: The number to be checked.

Returns:
True if the number is a perfect number, False otherwise.

Start from 1 because dividing by 0 will raise ZeroDivisionError.
A number at most can be divisible by the half of the number except the number
itself. For example, 6 is at most can be divisible by 3 except by 6 itself.

Examples:
>>> perfect(27)
False
>>> perfect(28)
True
>>> perfect(29)
False
>>> perfect(6)
True
>>> perfect(12)
False
>>> perfect(496)
True
>>> perfect(8128)
True
>>> perfect(0)
False
>>> perfect(-1)
False
>>> perfect(12.34)
Traceback (most recent call last):
...
ValueError: number must be an integer
>>> perfect("Hello")
Traceback (most recent call last):
...
ValueError: number must be an integer
"""
if not isinstance(number, int):
raise ValueError("number must be an integer")
if number <= 0:
return False
return sum(i for i in range(1, number // 2 + 1) if number % i == 0) == number

if __name__ == "__main__":
from doctest import testmod

testmod()
print("Program to check whether a number is a Perfect number or not...")
try:
number = int(input("Enter a positive integer: ").strip())
except ValueError:
msg = "number must be an integer"
print(msg)
raise ValueError(msg)

print(f"{number} is {'' if perfect(number) else 'not '}a Perfect Number.")
```  