Narcissistic numbers in Python

Question

I am beginner to the Python programming language and I have been using a website to help me exercise. It gave me this challenge to make a program that returns true if a given number is narcissistic or false otherwise.

Examples of narcissistic numbers:

153 (3 digits): 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153
1634 (4 digits): 1^4 + 6^4 + 3^4 + 4^4 = 1 + 1296 + 81 + 256 = 1634

But for some reason when the number 371 is given the function returns False instead of True.

The code:

def narcissistic(value):
    logical = True
    logical2 = True
    i = 0
    j = 0
    notation = 10
    sum = 0

    #Calculating the number notation 
    while logical:
        if 10 ** i <= value:
            notation = 10 ** i
            i = i + 1
        else:
            logical = False

    #i from now on is also the qauntity of digits
    while logical2:
        if ( notation / 10 ** j ) >= 1:
            sum = sum + ( value // ( notation / 10 ** j ) ) ** i
            j = j + 1
        else:
            logical2 = False

    if sum == value:
        return True
    else:
        return False

Answer 1

Your code is very close! The issue lies here:

sum = sum + ( value // ( notation / 10 ** j ) ) ** i

For 1634, this multiplies 1, 16, 163, and 1634. You need only the LSB of these numbers, in this example 1, 6, 3, and 4 - use the modulo operator to get this. If we mod them by 10 to get only the LSB...

sum = sum + (( value // ( notation / 10 ** j ) ) % 10) ** i

...then the code works perfectly.

Demo

Answer 2

It would probably be easier to do this task by converting the value to a string and back. Taking the length of the string is an easy way to get the number of digits ("the poor man's logarithm"), and you can easily iterate over individual digits:

def narcissistic(value):
    str_value = str(value)
    num_digits = len(str_value)
    return (value == sum(int(digit) ** num_digits for digit in str_value))

>>> narcissistic(153)
True
>>> narcissistic(1634)
True
>>> narcissistic(371)
True
>>> narcissistic(372)
False