Java Program to Find Prime Factor

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What is Prime Factor?

A Prime Factors of a given number is that any prime number other than 1 and itself that exactly divides the given number. For example, the prime factors of 60 is 2, 3, 5

Examples

The following table provides few examples of prime factors of a number.

NumberPrime Factors
555, 11
1002, 5
1862, 3, 31

Find Prime Factor

In the following example, we will find all the Prime factors of the given number (186).

Example

Java Compiler
public class myClass { public static void main(String[] args) { int num = 186; int i, j; int count = 0; int flag = 0; System.out.format("Prime factor of %d:\n", num); for(i=2; i<num; i++) { // check for divisibility if(num % i == 0) { count = 0; // check for prime number for(j=1; j<=i; j++) { if(i % j == 0) count++; } if(count == 2) { flag = 1; System.out.print(i +" "); } } } if(flag == 0) System.out.format("There is no Prime factor for %d ", num); } }

Output

Prime factor of 186: 2 3 31

Find Prime Factor of any Given Number

In the following example, we will find a prime factors of any given number.

Example

Java Compiler
import java.util.Scanner; public class myClass { public static void main(String[] args) { Scanner reader = new Scanner(System.in); System.out.print("Enter a (int) Number: "); int num = reader.nextInt(); int i, j; int count = 0; int flag = 0; System.out.format("\nPrime factors of %d:\n", num); for(i=2; i<num; i++) { // check for divisibility if(num % i == 0) { count = 0; // check for prime number for(j=1; j<=i; j++) { if(i % j == 0) count++; } if(count == 2) { flag = 1; System.out.print(i +" "); } } } if(flag == 0) System.out.format("There is no Prime factor for %d ", num); } }

Output

Enter a (int) Number: 45 Prime factors of 45: 3 5

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