Python: narcissistic (Armstrong) number

The problem

A narcissistic (Armstrong) number in base 10 equals the sum of its digits, each raised to the power of the number of digits.

Example — 153 has 3 digits:

1³ + 5³ + 3³ = 1 + 125 + 27 = 153  ✓

But 1652 (4 digits) does not:

1⁴ + 6⁴ + 5⁴ + 2⁴ = 1 + 1296 + 625 + 16 = 1938 ≠ 1652

The function should return True or False.

Approach

1. Count digits: power = len(str(value))
2. Sum int(digit) ** power for each digit
3. Compare with the original

A list comprehension does it in one line.

Solution

def narcissistic(value):
    power = len(str(value))
    return value == sum([int(number) ** power for number in str(value)])

Examples

print(narcissistic(153))   # True
print(narcissistic(1652))  # False
print(narcissistic(7))     # True
print(narcissistic(9474))  # True

Summary

One line with a list comprehension — a clean way to check whether a number "loves itself."