21 million bitcoins...100 million parts in each.How many parts in all?

$$21 million times 100 million is \\
$=21\times 10^6\times 100\times 10^6\\
$=2.1\times 10^7\times 10^8\\
$=2.1\times 10^{15}\\
$=2,100,000,000,000,000\\$$

2 quaddillon 100 trillion