Narcissistic Number Checker

How it is calculated

The tool takes the number you typed as a string of whole digits and counts them: len. It then adds up each digit raised to the power of that count, sum = d₁^len + d₂^len + … + d_len^len. If sum equals the number, the answer is Yes, otherwise No. The sum is always shown, so a near miss is visible: 154 gives 190. The input must be a whole number: a decimal such as 153.4 and any negative number give no result, as does a number above 9,007,199,254,740,992 (2⁵³). Zero and every single-digit number pass, because a digit to the power of 1 is itself. The check works in base 10 only.

Common mistakes

• Using the wrong power. The exponent is the number of digits of the number, not always 3. For 9474 it is 4: 9⁴ + 4⁴ + 7⁴ + 4⁴ = 9474.
• Typing a decimal such as 153.4 and expecting a verdict. Only whole numbers are tested, so a fractional value gives no result.
• Entering a negative number such as -153. The tool gives no result for negatives instead of testing the digits.
• Believing a digit sum that is close to the number counts. Only an exact match passes: 154 produces 190, which is not 154.
• Forgetting that single digits are narcissistic. 0 to 9 all return Yes, because each equals itself to the first power.