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Amicable Number Checker

Check whether two numbers are amicable — or give just one and get its candidate partner plus the verified loop, with perfect and sociable numbers identified.

Related tools

All Numbers & arithmetic tools →
e Digits Calculator (Euler's Number)Compute up to 1,000 decimals of Euler's number e from the series Σ 1/k!, with digit frequencies, a digit search and the 1828 1828 trap explained.Number of Digits CalculatorCount the digits of any integer in any base from 2 to 36, with the digit sum, product, first and last digit, and palindrome and repdigit flags.Number Pattern FinderFind the rule behind a sequence: arithmetic, geometric, quadratic, cubic, Fibonacci, powers, triangular, factorial, primes or a linear recurrence, with the difference table and the next terms.Prime number checkerCheck whether a number is prime and find its smallest divisor.Complex Number CalculatorAdd, subtract, multiply and divide complex numbers, with modulus, argument, conjugate and polar form.Fibonacci Number CheckerTest any number up to 60 digits with the exact 5n^2 +/- 4 identity, with its index, its neighbours in the sequence and the ratio compared with the golden ratio.Five Number Summary CalculatorGet the minimum, quartiles and maximum of a dataset with the IQR, the outlier fences and a box plot, in three quartile conventions.CalculatorEvaluate math expressions with parentheses, powers and modulo, live.

Amicable Number Checker is free to use as often as you like, directly from this page. It sits under Numbers & arithmetic in our catalogue, alongside e Digits Calculator (Euler's Number) and Number of Digits Calculator.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What is Amicable Number Checker?

Check whether two numbers are amicable — or give just one and get its candidate partner plus the verified loop, with perfect and sociable numbers identified.

When would I actually use this?

Reading a number written another way: a Roman numeral on a monument, a hexadecimal colour, a binary byte, or a fraction that needs reducing.

What is the most common mistake?

Assuming a decimal fraction survives a change of base. A tenth is exact in decimal and infinitely repeating in binary, which is why 0.1 + 0.2 is not 0.3 in most programming languages.

How is Amicable Number Checker different from e Digits Calculator (Euler's Number)?

They sit next to each other but answer different questions: e Digits Calculator (Euler's Number) is the one to open when you need it to compute up to 1,000 decimals of Euler's number e from the series Σ 1/k!, with digit frequencies, a digit search and the 1828 1828 trap explained. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Number of Digits Calculator is the closest one after this: Count the digits of any integer in any base from 2 to 36, with the digit sum, product, first and last digit, and palindrome and repdigit flags.

What else is worth having open alongside it?

Number Pattern Finder and Prime number checker — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Base conversion and number-theory results are exact. Roman numerals follow the standard subtractive form used since the Middle Ages, which is not the only one the Romans themselves used.

Further reading

All guides →
How-toHow to Round Numbers: Round Half Up, Round Half to Even, and MoreRound to any decimal place or number of significant figures, and learn when to use round half up versus round half to even to avoid bias.ExplainerSignificant Figures Explained: Counting, Rounding, and Why They MatterLearn what counts as a significant figure, the rules for leading, trailing, and captive zeros, and how sig figs keep your calculated answers honest.How-toHow to Find Prime Factors: Factor Trees and the Division MethodBreak any whole number into its prime building blocks with a factor tree or repeated division — and write the result as a clean prime factorization with exponents.How-toHow to Multiply and Divide Fractions: Multiply Across, Flip to DivideMultiplying fractions needs no common denominator — just multiply across. Dividing means multiplying by the reciprocal. Learn both with worked examples and how to simplify.How-toHow to Add and Subtract Fractions: Common Denominator, Combine, SimplifyYou can only add or subtract fractions that share a denominator. Learn to find a common denominator, combine the numerators, and simplify the result, with a worked example.How-toHow to Do Long Division: Divide, Multiply, Subtract, Bring DownLong division breaks a big division into a repeating four-step cycle. Learn the divide-multiply-subtract-bring-down loop and how to read the remainder, with a worked example.