Celebrities do not want random fans or anyone they don't know calling them. They like to keep certain things private, if he gave out his phone number (or any famous person did) just imagine how many hundreds of thousands of missed calls and text message, good and bad they would get. no one wants that. His phone number is private and his privacy should be respected. His address is probably unavailable too to keep him safe. I'm sure he has a fan mail address or a website or Facebook, twitter, ect where you can get more information about him. If you want to personally ask him a question though you need to understand that it's incredibly unlikely to happen.
He obviously doesn't want you to have it ... celebrities don't exactly make their contact info public.
Um, the rapper?