public static boolean isPrime(int number) {
		if (number < 0) {
			throw new IllegalArgumentException("Error: int cannot be < 0!");
		}
		int sqrt = (int) (Math.sqrt(number) + 1);

		if (number == 2) {
			return true;
		}
		if (number == 1) {
			return false;
		}
		for (int j = 2; j <= sqrt; j += 1) {
			if (number % j == 0) {
				return false;
			}
		}

		return true;
	}