Number Magic

Question :
What is an 'Abundant Number' ?

Answer :
When a number itself is greater than the sum of its factors, it is said to be an abundant number.
It can also be called excessive number or redundant number.
An abundant number is a positive integer n for which,
s(n) = s(n) - n > n,
where, s(n) is the divisor function and s(n) is the restricted divisor function and quantity s(n)-2n is sometimes called the abundance.
For Example,
The first few abundant numbers are 12, 18, 20, 24, 30, 36, ...