How to print Narcissistic(Armstrong) Numbers with Python?

A narcissistic number (also known as an Armstrong number) is a number that equals the sum of its digits, each raised to the power of the number of digits. For example, 370 = 3³ + 7³ + 0³ = 27 + 343 + 0 = 370.

Algorithm Steps

The algorithm to check for an Armstrong number follows these steps ?

• Determine the number of digits for the mentioned number.
• Extract each digit and calculate the power of that digit with the exponent equal to the number of digits.
• Calculate the sum of the power.
• Compare with the original number.

Finding Armstrong Numbers in a Range

Here are two different approaches to find Armstrong numbers within a given range ?

Method 1: Using Double Star Operator

The program below uses the double star operator (**) to calculate the power of the digits ?

for num in range(50, 1000):
    original = num
    total = 0
    n = len(str(num))
    
    while num > 0:
        digit = num % 10
        total += digit ** n
        num //= 10
    
    if total == original:
        print(original)

The output of the above code is ?

153
370
371
407

Method 2: Using pow() Function

This optimized approach uses the built−in pow() function and defines a reusable function ?

def is_armstrong(num):
    digits = str(num)
    n = len(digits)
    total = sum(pow(int(d), n) for d in digits)
    return total == num

# Print Armstrong numbers in the given range
for number in range(700, 10000):  
    if is_armstrong(number):
        print(number)

The output of the above code is ?

1634
8208
9474

Finding the First N Armstrong Numbers

This example finds and prints the first 10 Armstrong numbers ?

def is_armstrong(num):
    n = len(str(num))
    total = sum(int(digit) ** n for digit in str(num))
    return total == num

def first_n_armstrong(n):
    count = 0
    num = 1
    while count < n:
        if is_armstrong(num):
            print(num)
            count += 1
        num += 1

first_n_armstrong(10)

The output of the above code is ?

1
2
3
4
5
6
7
8
9
153

Comparison

Conclusion

Armstrong numbers can be efficiently found using either the ** operator or pow() function. The generator expression approach with sum() provides the most concise and readable solution for checking Armstrong numbers.