What are the perfect numbers?

A perfect number is a natural number that is equal to the sum of its proper divisors.

They are closely related to the Mersenne prime numbers and there are several theorems that have made it possible to find them, including those of Euclid and Fermat.

Perfect numbers  are quite rare; currently, only 50 are known. Those that we know are all pairs and there are only three between 0 and 1000: 6, 26 and 496.

Scientists are unable to tell whether there are odd . On the other hand, there are also tri-perfect, multi-and hyper-.