It's also the name of the program that implements the LLR algorithm. We use LLR to test the primality of many large numbers. It's downloaded automatically when an LLR task is sent to your computer.
In the project preferences web page, you select which projects you want to run. In the order they appear on the page, there's AP27, a dozen LLR projects, 2 sieve projects, and 9 GFN projects.
My lucky number is 75898524288+1 (I am NOT an administrator anymore, so please don't PM me with questions. I can't help.)