Prime Check program

import java.util.Scanner;

public class PrimeCheck {
    public static void main(String[] args) {
        Scanner amit = new Scanner(System.in);

        System.out.print("Enter a number: ");
        int num = amit.nextInt();

        boolean isPrime = true;

        if (num <= 1) {
            isPrime = false; // 0, 1, and negatives are not prime
        } else {
            for (int i = 2; i <= Math.sqrt(num); i++) { // check divisibility up to sqrt(num)
                if (num % i == 0) {
                    isPrime = false;
                    break;
                }
            }
        }

        if (isPrime) {
            System.out.println(num + " is a prime number.");
        } else {
            System.out.println(num + " is not a prime number.");
        }

        amit.close();
    }
}