A number is a Perfect Square if it can be expressed as k^2 for some positive
integer k. A number is a Perfect Power if it can be expressed as k^n (k to the n^{th} power) for some positive integers k and n, where n and k must both be greater than 1.
Create a class Powerful that contains the method power that takes an int, number, as
input and returns the String "<k>^<n>", where <k> to the <n>^{th} power is equal to number. If a number cannot be represented as a Perfect Power, your method should return "NOT A PERFECT POWER".
