I'll pick 5847 please.
Also, thanks for this contest. It gave me a program idea. I started making it(c++) and what it's gonna do is you out in number, and name, of people here, it'll output to a text file. Nice and organized, it'll tell you if number is already taken. I'm planning on making it so it will read through the numbers, and go through some equations to find the best number to choose(in the middle of the biggest number gap)
I'll keep updating my progress whenever I post here again. So far I've got the name and number and checking. Working on making it better and soon I'll be getting the equations part in. Only doesn't 40 Minutes trying to refresh my memory on c++. So yea.
I'm really tired so I post weird stuff like this.