Armstrong Number Checker
Check whether a number is an Armstrong (narcissistic) number, equal to the sum of its own digits each raised to the power of the digit count.
Last reviewed by the Radiatus Cloud team
Check whether a number is an Armstrong (narcissistic) number.
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Check for an Armstrong number
An Armstrong number, also called a narcissistic number, is a number that equals the sum of each of its digits raised to the power of the number of digits. This checker computes that sum and compares it with the original number. The classic example is one hundred and fifty-three, which has three digits, and one cubed plus five cubed plus three cubed equals one hundred and fifty-three. Single-digit numbers are trivially Armstrong numbers.
The tool shows the digit count and the computed sum so you can see exactly why a number does or does not qualify.
Narcissistic numbers
Armstrong numbers are called narcissistic because they are, in a sense, built from themselves. There are only a finite number of them in each base, and they thin out quickly as numbers grow larger. Three-digit Armstrong numbers include one hundred and fifty-three, three hundred and seventy, three hundred and seventy-one, and four hundred and seven. They are a favourite exercise for learning loops and digit handling in programming.
The power used is always the total number of digits, which is what distinguishes Armstrong numbers from similar digit-based curiosities. All calculation happens locally in your browser.
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Frequently Asked Questions
What is an Armstrong number?
A number equal to the sum of its digits each raised to the power of the total number of digits, such as one hundred and fifty-three.
Why is it also called narcissistic?
Because the number is reconstructed from its own digits, it is said to be in love with itself, hence the name narcissistic number.
Are single-digit numbers Armstrong numbers?
Yes. Any single digit raised to the power one equals itself, so every single-digit number trivially qualifies.
How many Armstrong numbers are there?
A finite number in each base. In base ten the three-digit ones are 153, 370, 371 and 407, and they become rarer as numbers grow.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Enter a positive integer to check if it is an Armstrong number.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.