Euler Problem 49 solution

Time (s): ~0.002

package margusmartseppcode.From_40_to_49;

import java.util.Arrays;

public class Problem_49 {

 // Call only if: (n>0&&(i%2==0||i%3==0||i%5==0||i%7==0))
 static boolean isPrimeS(final int n) {
  final int r = (int) Math.floor(Math.sqrt(n));
  for (int f = 5; f <= r; f += 6)
   if (n % f == 0 || n % (f + 2) == 0)
    return false;
  return true;
 }

 static boolean isPerm(char[] a, char[] b) {
  if (a.length != b.length)
   return false;
  Arrays.sort(a);
  Arrays.sort(b);
  return Arrays.equals(a, b);
 }

 static boolean arePerms(int... n) {
  if (n.length == 0)
   return true;
  for (int i = 1; i < n.length; i++)
   if (!isPerm(("" + n[i - 1]).toCharArray(), ("" + n[i])
     .toCharArray()))
    return false;
  return true;
 }

 static boolean arePrimes(int... n) {
  for (int i : n)
   if (!isPrimeS(i))
    return false;

  return true;
 }

 public static void main(String[] args) {
  int a, b, c;
  a = b = c = 0;

  for (a = 1489;; a += 2) {
   if (a % 3 == 0 || a % 5 == 0 || a % 7 == 0)
    continue;
   
   b = a + 3330;
   c = a + 6660;

   if (arePrimes(a, b, c))
    if (arePerms(a, b, c))
     break;
  }
  System.out.println("" + a + b + c);
 }
}