Soulja Boy More Money than God ... If God Was Chief Keef.

Soulja Boy is 23 years old and has more money in his sweat pants than you'll see in a year ... which he happily showed off .

Soulja was strollin' around in LA Saturday when a camera man asked if he was still celebrating his bday (it was July 28) -- at which point Soulja went all Chief Keef on him and flashed some bills.

By "some" bills -- we mean STACKS and STACKS and STACKS of cash. Possibly more than Keef.

As for why he walks around so pocket-heavy -- we'll let him explain. It sort of makes sense