If you're evil, don't forget the mind control center. 100% bonus to economy, twice that of the economic capital.
You can go higher on the farms, but it does take a long time for the planet to fully develop that way. My max so far has been a bit over 60 billion people. No real issue keeping them in line since there were 42 tiles on the planet and plenty of development (class 26 base, +42% planet quality event = 36, +6 from terraforming = 42). IIRC there were 15x stock exchanges, 8x farms (I'd buy more as the pop grew), and around 10 virtual reality centers (probably more than I needed, even with my 69% tax rate). With the econ capital and mind control center, it was producing over 2k bc per turn, and still growing. And during most of that game, there was the "increased econ" event that pushed its income to around the 3.5k mark. I have the exact numbers written down somewhere, but can't find them at the moment.