We could say there are ONLY 21 THOUSAND bitcoins, and have them subdividable like 11 decimal points. Just to put a perspective on the arbitrariness of how we define the limit.

Actual BTC limit = 21000000.00000001

Could just as easily be: 21000.00000000001

Or even: 21.00000000000001  (only 21 bitcoins in existance! lol)

So, we could say "21 thousand bitcoins ONLY!" But does that mean there are only 21 thousand bitcoins? No.

They're all the SAME QUANTITY of UNITS allowable. Pretty arbitrary really.

Just food for thought.