### What are Perfect Numbers ?

Perfect numbers are the natural numbers, whose sum of positive divisors (excluding the number itself) is equal to the number itself.Also, it means that sum of all the factors of the number (including itself) is twice the number.**, because 1, 2, and 3 are its proper positive divisors, and 1 + 2 + 3 = 6. Equivalently, the number 6 is equal to half the sum of all its positive divisors: ( 1 + 2 + 3 + 6 ) / 2 = 6.**

*The first perfect number is 6*List of first few perfect numbers are

6 = 1 + 2 + 3

28 = 1 + 2 + 4 + 7 + 14

496 = 1 + 2 + 4 + 8 + 31 + 62 + 124 + 248

Euclid discovered that the first four perfect numbers are generated by the formula 2

^{p−1}(2

^{p}−1), with p a prime number:

for p = 2: 2

^{1}(2

^{2}−1) = 6

for p = 3: 2

^{2}(2

^{3}−1) = 28

for p = 5: 2

^{4}(2

^{5}−1) = 496

for p = 7: 2

^{6}(2

^{7}−1) = 8128.

Noticing that in each of these cases 2

^{p}−1 is a prime number, Euclid proved that 2

^{p−1}(2

^{p}−1) is an even perfect number whenever 2

^{p}−1 is prime .

Perfect Number Chart |

*Read*

*Grievances of A Software**(Just 4 Fun)*

*Copyright © ianswer4u.com***Read More:-**

What is a prime number ?

What are Even and odd numbers ?

Perfect Numbers Definition