Given an integer n, return true if it is a power of three.
The largest power of 3 that fits in a 32-bit integer is 3^19 = 1162261467. Any n that is a power of 3 must divide this number.
- If n <= 0: return false.
- Return 1162261467 % n == 0.
- Time Complexity: O(1)
- Space Complexity: O(1)