👉 In mathematics, a perfect number is a positive integer that is equal to the sum of its proper divisors (excluding itself). The first few examples are 6 = 1 + 2 and 4 = 1 + 2. Perfect numbers are interesting because they have many properties in common with prime numbers, but also some unique properties. Perfect numbers were discovered by ancient mathematicians such as Euclid. They are named after the Greek mathematician Pythagoras who first described them in his
