Perfect number

A perfect number is a number for which the sum of its proper factors is equal to the number itself.

proper factor

The proper factors of a number are all its factors except the number itself.


6 is a perfect number because the sum of its proper factors (1, 2, and 3) is equal to 6.

Did you know?

Perfect numbers have been studied since ancient times. The early Egyptians are believed to have studied perfect numbers. Pythagoras, a famous Greek mathematician and philosopher, studied them, perhaps from a metaphysical (nonphysical) as well as a mathematical perspective. There is still much to learn about perfect numbers, and mathematicians still study them today.