Contacting Bianchi USA like demoncyclist suggests is definitely a good place to start. Not only may they be able to confirm the bike's authenticity based on the serial number, but they could tell you what model it is and maybe even sell you a derailleur hanger while they're at it.

The Bianchi USA web site doesn't seem to have any contact info on it, but you can try calling them at (510) 264-1001.