21 million BTC might seem insufficient with a global population of 7 billion people, the bitcoin currency is highly divisible. The smallest denomination allowed by the current software is 0.00000001 BTC (10-8 BTC), which has been defined as 1 satoshi and was named after the software’s putative creator, Satoshi Nakamoto. There are therefore 100 million satoshis in a single bitcoin, and thus the maximum supply of 21 million BTC will be equal to 2.1 quadrillion satoshis or, if you prefer, 2,100 trillion satoshis.