Its 92,000,000,000 ?
Int64's Max value is 9,223,372,036,854,775,807
But MAX_MONEY is multiply by satoshi, ( * COIN ) so it multiply by 10,000,000, right?
Then so max possible total coin supply (MAX_MONEY) is approx 92,000,000,000?
As has been explained before in this forum, that's just an integer overflow check.
The number of coins isn't explicitly stated but depends on the block reward and halving schedule.