Perfect Number/Examples/28

Example of Perfect Number
$28$ is a perfect number:
 * $1 + 2 + 4 + 7 + 14 = 28$

Proof
Thus $28$ is in the form $2^{p - 1} \paren {2^p - 1}$.

$\paren {2^3 - 1} = 7$ is prime.

So $28$ is perfect by the Theorem of Even Perfect Numbers.

The aliquot parts of $28$ are enumerated at.
 * $1, 2, 4, 7, 14$