I'm going to venture out and say that if you had to ask this question, you're probably not ready to purchase an apartment complex in Phoenix.
Think about it... when you play Monopoly you buy the little green houses first, then the big red hotels. There's A LOT that can go wrong between tenants, toilets and termites... and having 16 to deal with instead of just one can make for a lot more stress than you're hoping for.
That all being said, not trying to dissuade you, but perhaps a single family home at a much lower price would be far less risky and offer you more opportunity to find a deal with such terms.