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Livable as in breathable?
As far as we know you need life to have oxygen (and low CO2).
Also you may want to care about the core, without one able to produce the right magnetic field your atmosphere is fucked.
If you want the right temperature, pressure and all, you pretty much want Earth 2.
For a much smaller body to retain atmosphere you need to get away from the sun, like Titan.
The price to pay is to be fucking cold and obviously the atmosphere isn't breathable.
