Can i have a rat with 3 cats in the house?

Hi i want to adopt a rat. But there is one itty bitty problem, well its kinda big :( i have 3 cats who 2 of them are 3yrs and one 2yrs old. I want a cute 4 month old rat. But I have my cats. How safe is it? I will be putting him in a place unclimbable and not short high up about 3ft. 11.inch idk metric sorry:(. Please answer soon!