Project Euler Problem 3: Largest prime factor

Problem

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

What is the largest prime factor of the number 600851475143?

Solution


If the while loop condition changes to divisor < number, it will be extremely slow for number like 600851475145

      public static void main(String[] args) {            
           long number = 600851475143L;  
           long divisor = 2;  
           while((divisor * divisor) <= number){  
                if(number%divisor==0){  
                     number = number/divisor ;  
                }  
                divisor++;  
           }  
           System.out.println(number);  
      }