title: Next prime number algorithm
body: <p>i want to know if there is a easy way to find the prime number next to X.</p>
  
  <p>For example, if X=2, the next prime will be 3. The algorithm that i have would be ok, if i wanted to know little numbers but i want to calculate like X=3 million.</p>
  
  <p>I found a algorithm to calculate primes, but it takes a lot of time to calculate them, since it calculates all primes from 0 to X... For example for 1 million, it takes almost 2 minutes.</p>
  
  <p>Question is... How can i find the next prime number? Is there an efficient algorithm? Best solution i found is to check if X+1 is prime and increase until one is found...</p>