Problem 3 of largest prime factor

The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143 ?

http://projecteuler.net/problem=3

public class PrimeNum {
	public static void main(String args[]){
		double l=600851475143.0;
		
		for(double i=2;i<l;i++){
			if(l%i==0){
				if(isPrime(l/i)){
					System.out.println("l%i="+l/i);
					break;
				}
			}
		}
	}
	
	  public static boolean isPrime(Double n){  
	        for(int i = 2; i * i <= n; i++){  
	      if(n % i == 0)  
	       return false;  
	      }  
	        return true;  
	    }
}	

Answer:

6857