I don't know about the US but here a landlord can't enter your appartment without like a week, or if it's even more, heads up. The only time they can go in on shorter notice is if the other appartments are under direct and immediate danger like there is a fire or water leak and noone is responding when they ring the doorbell.
So here you are pretty safe renting.
What are the rules concerning rented appartments and this in the states?
Puffzter
