It is enough for it .it was planned very well and executes too .there are 8 units for satoshi .it is more than enough for some people .by the time the price of bitcoins would reach up to a maximum height .
Even though you can split a Bitcoin down to 8 decimal places, you can't really send just 1 satoshi. What would the fee be for that transaction? Even if the fee was 1 satoshi, the fee would be 100% of the transaction price. For that reason, we can't really say that we can break a Bitcoin down to that small of an amount.
yes that is really a big digit and we can have even a very small unit of it and that is the reason that i can say that the 21 millions is really a big amount for the world world