Armstrong Number in C Programming


In the world of programming, there are various intriguing concepts and algorithms that programmers encounter in their journey. One such concept is the Armstrong Number in C Programming.

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This article aims to provide a comprehensive understanding of Armstrong numbers, how they work, and how they can be implemented using the C programming language.

What is an Armstrong Number?

An Armstrong number, also known as a narcissistic number or pluperfect digital invariant, is a special type of number that is equal to the sum of its own digits raised to the power of the number of digits it contains.

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Let’s take an example to illustrate this concept. Consider the number 153. It has three digits: 1, 5, and 3.

If we raise each digit to the power of three (the number of digits), we get 1^3 + 5^3 + 3^3, which equals 153. Therefore, 153 is an Armstrong number.

How to Determine if a Number is an Armstrong Number in C Programming

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To determine whether a given number is an Armstrong number in C programming, we need to follow a set of steps.

Let’s break it down:

  1. Accept the number as input from the user.
  2. Calculate the number of digits in the input number.
  3. Initialize a variable to store the sum of the digits raised to the power of the number of digits.
  4. Extract each digit from the input number using modulus and division operations.
  5. Raise each digit to the power of the number of digits and add it to the sum.
  6. Compare the calculated sum with the input number.
  7. If the sum is equal to the input number, it is an Armstrong number; otherwise, it is not.

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Here’s a C program that implements the above steps:

#include <stdio.h>
#include <math.h>

int main() {
    int number, originalNumber, remainder, result = 0, n = 0;

    printf("Enter an integer: ");
    scanf("%d", &number);

    originalNumber = number;

    while (originalNumber != 0) {
        originalNumber /= 10;

    originalNumber = number;

    while (originalNumber != 0) {
        remainder = originalNumber % 10;
        result += pow(remainder, n);
        originalNumber /= 10;

    if (result == number)
        printf("%d is an Armstrong number.", number);
        printf("%d is not an Armstrong number.", number);

    return 0;

Exploring Armstrong Numbers in C Programming

Now that we have understood the basics of Armstrong numbers and how to determine if a number is an Armstrong number in C programming.

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Let’s explore some additional aspects.

Why are Armstrong Numbers Interesting?

Armstrong numbers are fascinating because they showcase a unique mathematical property.

The fact that a number can be equal to the sum of its own digits raised to a power is intriguing.

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These numbers have been a subject of curiosity and exploration for mathematicians and programmers alike.

Finding Armstrong Numbers in a Given Range

Apart from checking if a specific number is an Armstrong number, programmers often encounter scenarios where they need to find Armstrong numbers within a given range.

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This can be achieved by extending the earlier program to iterate through the range and check each number for the Armstrong property.

Optimizing the Armstrong Number Calculation

The above implementation calculates the power of each digit individually, which can be computationally expensive for larger numbers.

However, we can optimize the process by storing the powers of digits in an array and using it for calculations.

This reduces the number of repeated computations and improves the efficiency of the program.

Frequently Asked Questions (FAQs)

Q: What is the significance of the name “Armstrong Number”?

The name “Armstrong Number” is derived from a puzzle published by Michael F. Armstrong in 1966. It involved finding numbers that satisfy the properties described earlier. Since then, these numbers have been referred to as Armstrong numbers.

Q: Can negative numbers be Armstrong numbers?

No, Armstrong numbers are defined only for positive integers. Negative numbers and fractions are not considered Armstrong numbers.

Q: Are there any Armstrong numbers beyond a certain range?

Armstrong numbers can exist for any range of integers. However, as the range increases, the frequency of Armstrong numbers becomes increasingly rare.

Q: How can Armstrong numbers be used in real-world applications?

Armstrong numbers, although primarily a mathematical curiosity, can have applications in various fields such as cryptography, data security, and error detection.

Q: Are Armstrong numbers unique?

Yes, Armstrong numbers are unique within their range. Each Armstrong number has its own distinct combination of digits that satisfies the properties of an Armstrong number.

Q: Can Armstrong numbers be negative?

No, by definition, Armstrong numbers are non-negative integers. Negative numbers cannot be Armstrong numbers.


In conclusion, Armstrong numbers are a captivating mathematical concept that can be implemented using the C programming language.

These numbers possess a unique property where they are equal to the sum of their own digits raised to the power of the number of digits.

Understanding the logic behind Armstrong numbers and being able to determine whether a number is an Armstrong number or not is a valuable skill for programmers.

Whether it’s solving puzzles or exploring applications in various domains, Armstrong numbers continue to intrigue and challenge the minds of programmers worldwide.