Nth Prime Number and Sum of Primes

NthPrimeNumber.java

public class NthPrime
{
  public static void main(String[] args)
  {
    int curr = 0;
    int count = 1;
    for (int i = 3; count < 10001; i+=2){
      if (isPrime(i)){
        count++;
        curr = i;
      }
    }
    
    
    System.out.print("10001th prime: " + curr);
  }
  
  public static boolean isPrime(int n) {
    if (n == 2) return true;
    //check if n is a multiple of 2
    if (n%2==0) return false;
    //if not, then just check the odds
    for(int i=3;i*i<=n;i+=2) {
      if(n%i==0)
        return false;
    }
    return true;
  }
}

//output:
//10001th prime: 104743

//To optimize, use:
//http://www.algolist.net/Algorithms/Number_theoretic/Sieve_of_Eratosthenes


public class SumOfPrimes
{
  public static void main(String[] args)
  {
    long sum = 2;
    for (long i = 3; i < 2000000; i+=2){
      if (isPrime(i)){
        sum += i;
      }
    }
    
    
    System.out.print("sum of primes under 2 million: " + sum);
  }
  
  public static boolean isPrime(long n) {
    if (n == 2) return true;
    //check if n is a multiple of 2
    if (n%2==0) return false;
    //if not, then just check the odds
    for(int i=3;i*i<=n;i+=2) {
      if(n%i==0)
        return false;
    }
    return true;
  }
}

/*output:
sum of primes under 2 million: 142913828922
*/