Soma dos Divisores (σ)

σ(n) = Σ d|n d.
Created by
Renato Passos, Eng. de Software
Reviewed by
Renato Passos, Eng. de Software

Last updated: Apr 18, 2026

σ(n)
28

Formula

soma divisores

About this calculator

The Sum of Divisors (σ) calculator computes the sum of all positive divisors of a natural number n. For example, for n = 6, the divisors are 1, 2, 3, and 6, and the sum σ(6) = 12. This function is classic in number theory and appears in divisibility problems and perfect numbers.

The operation is simple: enter a positive integer and the tool finds all its divisors, summing them. The formula σ(n) = Σ d|n d is implemented by an efficient algorithm that tests divisors up to the square root of n. The result is displayed along with the list of divisors, when applicable.

Use this calculator to check if a number is perfect (σ(n) = 2n), deficient (σ(n) < 2n), or abundant (σ(n) > 2n). It is also useful in school math problems, contests, and studies of numerical sequences. For example, numbers like 6, 28, and 496 are perfect because the sum of their divisors (excluding the number itself) equals the number.

Caveats: the sum includes the number itself. For the sum of proper divisors (function s(n) = σ(n) - n), subtract n manually. Also, the tool works only for positive integers. Avoid very large numbers (above 10^9) to prevent processing overload.

Frequently asked questions

What is the σ(n) function in mathematics?

σ(n) is the sum of all positive divisors of n, including 1 and n itself. It is a multiplicative function used in number theory.

How do I know if a number is perfect using this calculator?

A number is perfect if σ(n) = 2n. For example, for n=6, σ(6)=12, which is 2×6, so 6 is perfect.

Does the calculator show the list of divisors?

Yes, besides the sum, the tool displays all divisors found, making verification easy.

Can I use decimal or negative numbers?

No. The calculator accepts only positive integers. For other types, the function is not defined.

What is the size limit for the number?

It is recommended to use numbers up to 10^9 for speed. Larger numbers may cause slowness.

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