If a 2-leaf door (actually French windows) counts as one, then 6, otherwise 8. Only me here, though I believe that both the similar apartments in this building have two occupants.

I feel that area might be a better measure, though how well the space is laid out makes a big difference. My present home, a recent build, is very efficiently laid out, and feels plenty big enough at 60sq metres, that's about 646sq ft.
My last place was slightly larger (about 5percent) but being around 250 years old was less efficiently laid out. It felt far less spacious, and has 10 doors.