How to calculate prime numbers.

 public class PrimalityTest {
   public static void main(String[] args) {
     long nearest = findNearest(124981242424L);
     System.out.println(nearest);

     long[] primes = nextPrimes(124981242424L, 10);
     System.out.println("Next 10 primes: ");
     for (int i = 0; i < primes.length; i++) {
         System.out.print(primes[i] + ",");
      } 
  }

  private static long[] nextPrimes(long num, final int count) {
    long[] primes = new long[count];
    int localCount = 0;
    for (long number = num;; number++) {
        if (isPrime(number)) {
            primes[localCount++] = number;
            if (localCount == count)
                break;
        }
    }
    return primes;
  }

  private static long findNearest(long num) {
    long nearestLarger = -1;
    for (long num2 = num;; num2++) {
       if (isPrime(num2)) {
            nearestLarger = num2;
            break;
        }
    }
    long nearestSmaller = -1;
    for (long num2 = num;; num2--) {
        if (isPrime(num2)) {
            nearestSmaller = num2;
            break;
        }
    }
    if (nearestLarger - num > num - nearestSmaller) {
        return nearestSmaller;
    }
    return nearestLarger;
  }

  public static boolean isPrime(final long num2) {
     if (num2 <= 3)
        return true;

     if ((num2 & 1) == 0)// check divisibility by 2
        return false;

     double sqrt = Math.sqrt(num2);
     for (long i = 3; i <= sqrt; i += 2)
        if (num2 % i == 0)
            return false;

      return true;
    }
  }

In Maple:

. x:= 124981242424:
  to 10 do x:= nextprime(x) end do;