The Great Internet Mersenne Prime Search project -- or GIMPS as it unfortunately refers to itself -- has counted to a new number. It's the new highest prime number we've yet discovered, somehow numbering a ludicrous 22,338,618 digits in length.
If you want to see it there's an equally bonkers 10.2MB zip file of the number in question to download, a number you can then print out and wallpaper an entire house with. It's officially written as 274207281-1 should you want to impress someone who knows about numbers, like a tax inspector or a bank manager.
Confirmation of the proof took "31 days of non-stop computing on a PC with an Intel I7-4790 CPU" according to the counter, although, if you have something more powerful, it can be computed in a matter of days -- as long as you're not also streaming stuff at the same time. [GIMPS via Cnet]