Project Euler #5 solved in Java

Project Euler question 5 is:

2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.

What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?

My Java solution is:

long c = 21;
while (1==1)
{
    boolean all = true;
    for (int i = 1; i < 21; i++)
    {
        all = true;
        if ( c % i != 0 )
        {
            all = false;
            break;
        }
    }
    if ( all )
    {
        System.out.println( c );
        System.exit(0);
    }     c++;
}