Python Program to Check Krishnamurthy Number

maths/krishnamurthy_number.py

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+"""
+ == Krishnamurthy Number ==
+It is also known as Peterson Number
+A Krishnamurthy Number is a number whose sum of the
+factorial of the digits equals to the original
+number itself.
+
+For example: 145 = 1! + 4! + 5!
+    So, 145 is a Krishnamurthy Number
+"""
+
+
+def factorial(digit: int) -> int:
+    """
+    function to calculate factorial of each digit
+    """
+
+    return 1 if (digit == 0 or digit == 1) else (digit * factorial(digit - 1))
+
+
+def krishnamurthy(number: int) -> bool:
+    """
+    >>> krishnamurthy(145)
+    True
+
+    >>> krishnamurthy(240)
+    False
+
+    >>> krishnamurthy(1)
+    True
+    """
+
+    factSum = 0
+    duplicate = number
+    while duplicate > 0:
+        factSum += factorial(duplicate % 10)
+        duplicate //= 10
+    return factSum == number
+
+
+if __name__ == "__main__":
+    print("Program to check whether a number is a Krisnamurthy Number or not")
+    number = int(input("Enter number: ").strip())
+    print(
+        f"{number} is {'' if krishnamurthy(number) else 'not '} a Krishnamurthy Number."
+    )

maths/perfect_number.py

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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:
+    """
+    >>> perfect(27)
+    False
+    >>> perfect(28)
+    True
+    >>> perfect(29)
+    False
+
+    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.
+    """
+    return sum(i for i in range(1, ((number // 2) + 1)) if number % i == 0) == number
+
+
+if __name__ == "__main__":
+    print("Program to check whether a number is a Perfect number or not.......")
+    number = int(input("Enter number: ").strip())
+    print(f"{number} is {'' if perfect(number) else 'not '} a Perfect Number.")