Write a Python Program to Check Armstrong Number

Last Updated on 16 March 2025

An Armstrong number (also known as a narcissistic number) is a number that is equal to the sum of its own digits each raised to the power of the number of digits.

For example, 153 is an Armstrong number because:

1³ + 5³ + 3³ = 1 + 125 + 27 = 153

In this tutorial, we will write a Python program to check whether a number is an Armstrong number or not.

What is an Armstrong Number?

A number n is an Armstrong number if:

\[\text{sum of (each digit ^ total digits)} = \text{original number}\]

Examples of Armstrong Numbers:

✔ 3-digit Armstrong numbers: 153, 370, 371, 407
✔ 4-digit Armstrong numbers: 9474, 8208

Python Program to Check Armstrong Number

# Taking user input
num = int(input("Enter a number: "))

# Convert number to string to count digits
num_digits = len(str(num))

# # Initialize variables
sum_of_powers = 0
temp = num

while temp > 0:
    digit = temp % 10
    sum_of_powers += digit ** num_digits
    temp //= 10

# Check if it is an Armstrong number
if sum_of_powers == num:
    print(num, "is an Armstrong number.")
else:
    print(num, "is not an Armstrong number.")

Output 1

Enter a number: 153
153 is an Armstrong number.

Output 2

Enter a number: 123
123 is not an Armstrong number.

Check Armstrong Number for a Range of Numbers

If you want to find all Armstrong numbers within a given range, use this program:

# Taking user input
lower = int(input("Enter the lower range: "))
upper = int(input("Enter the upper range: "))

print(f"Armstrong numbers between {lower} and {upper} are:")

for num in range(lower, upper + 1):
    num_digits = len(str(num))
    sum_of_powers = sum(int(digit) ** num_digits for digit in str(num))

    if sum_of_powers == num:
        print(num, end=" ")

Output

Enter the lower range: 100
Enter the upper range: 1000
Armstrong numbers between 100 and 1000 are:
153 370 371 407