I know this program isn't groundbreaking but after looking at simple prime number calculators online I decided to create my own. On my machine I was able to enter numbers as high as 18 or 19 digits (although you don't want a very large range!). My website is completely unknown so I was just hoping for some feedback on this, and possibly making it known to anyone who may find it handy.
It runs on Windows and requires .NET framework 2.0 or greater. As long as you have an updated version of Windows it should work