Emeraldstar and TenantNet are giving you good advice -- at least look into the possibility that your apartment is not legal -- it happens all the time, and just because the apartment seems to you like any other apartment (and you probably wouldn't have rented it if you thought something was amiss) does not mean that there are not red-flags here.
Help yourself and do your homework -- you can start by searching HPD and DOB for violations at your address. Check the certificate of occupancy -- there are a number of things you can do without moving away from your computer.
Just because you don't believe that you are in an illegal apartment, doesn't mean that you are not. Confirm your belief, and if you're right -- great! If not, the information you find will help form your course of action. But don't dismiss out of hand the suggestions made here about potential illegality -- the suggestions come from pretty knowledgeable and informed sources.