**Perfect number**, a positive integer that is equal to the sum of its proper divisors. The smallest perfect number is 6, which is the sum of 1, 2, and 3. Other perfect numbers are 28, 496. The discovery of such numbers is lost in prehistory. It is known, however, that the Pythagorean (founded *c.* 525 BCE) studied perfect numbers for their “mystical” properties.

**Explanation why 6 is Perfect Number**

The proper divisors of 6 are 1,2,3 as mentioned above

The sum of 1,2,3 i.e. 1+2+3 = 6 which is equal to the number we have with us i.e. 6.

Hence, 6 is Perfect Number.

Similarly, 496 is Perfect Number

The proper divisors of 496 are 1,2,4,8,16,31,62,124,248

The sum of 1,2,4,8,16,31,62,124,248 i.e. 1+2+4+8+16+31+62+124+248 = 496 which is equal to the number 496