Prime Number

/*
 * Problem : Check if a number is a prime number.
 * Input   : One integer.
 * Output  : true or false.
 * Approach: Look for a divisor.
 * Time    : O(sqrt(n))
 * Space   : O(1)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method receives a number and returns true if the number is a prime number.
    static boolean isPrime(long number) {
        // Step 1: Numbers smaller than 2 are not prime.
        if (number < 2) {
            return false;
        }

        // Step 2: If number = a * b and a is smaller than b, then a is at most the square root of the number.
        // So we only test divisors while divisor * divisor <= number.
        for (long divisor = 2; divisor * divisor <= number; divisor++) {
            // Step 3: If a divisor divides the number without remainder, the number is not prime.
            if (number % divisor == 0) {
                return false;
            }
        }

        // Step 4: No divisor was found, so the number is prime.
        return true;
    }

    public static void main(String[] args) {
        long number = new Scanner(System.in).nextLong();
        System.out.println(isPrime(number));
    }
}