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# Java Program to Check Whether a Number is Prime or Not

In this article, we will understand how to check whether a number is prime or not. Prime numbers are special numbers who have only two factors 1 and itself and cannot be divided by any other number. A number is a prime number if its only factors are 1 and itself. 11 is a prime number. Its factors are 1 and 11 itself. Some examples of prime numbers are 2, 3, 5, 7, 11, 13 and so on. 2 is the only even prime number. All other prime numbers are odd numbers.

Below is a demonstration of the same −

**Input**

Suppose our input is −

Enter the number : 47

**Output**

The desired output would be −

The number 47 is a prime number.

## Algorithm

Step 1 - START Step 2 - Declare a integer value namely my_input. Step 3 - Read the required values from the user/ define the values Step 4 - Using a for loop, check if the number is divisible by any of its lower numbers except 1. If no, it is a prime number. Else it’s not a prime number. Step 5 - Display the result Step 6 - Stop

## Example 1

Here, the input is being entered by the user based on a prompt. You can try this example live in our coding ground tool .

import java.util.Scanner; public class IsPrime { public static void main(String[] args) { int my_input; System.out.println("Required packages have been imported"); Scanner my_scanner = new Scanner(System.in); System.out.println("A reader object has been defined "); System.out.print("Enter the number : "); my_input = my_scanner.nextInt(); boolean isprime = false; for (int i = 2; i <= my_input / 2; ++i) { if (my_input % i == 0) { isprime = true; break; } } if (!isprime) System.out.println("The number " +my_input + " is a prime number."); else System.out.println("The number " +my_input + " is not a prime number."); } }

## Output

Required packages have been imported A reader object has been defined Enter the number : 47 The number 47 is a prime number.

## Example 2

Here, the integer has been previously defined, and its value is accessed and displayed on the console.

public class IsPrime { public static void main(String[] args) { int my_input = 47; System.out.println("The number is defined as " +my_input); boolean isprime = false; for (int i = 2; i <= my_input / 2; ++i) { if (my_input % i == 0) { isprime = true; break; } } if (!isprime) System.out.println("The number " +my_input + " is a prime number."); else System.out.println("The number " +my_input + " is not a prime number."); } }

## Output

The number is defined as 47 The number 47 is a prime number.

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