I was just having a read through some of the recently released email history between Satoshi and Martii 'Sirius' Malmi. I only just became aware of these, so thought I'd share in case others had missed/are interested:
https://twitter.com/pete_rizzo_/status/1761040089075888292One question I've always had is why he picked 21 million? Why not a round number, like 50m or 100m? And why is a Satoshi 100 millionth of a BTC and not a 10 millionth or a 1,000 millionth? Did he make assumptions about future value and therefore the minimum required 'value' of a satoshi relative to fiat?
Curious.
You've probably done a Google but this Quora (such an awful awful site...) answer seems plausible.
There has been a lot of speculation why the number 21 was chosen.
It could be symbolic. In 2008 the global M1 money supply was estimated at $21 trillion.
An interesting explanation was suggested by Christian Seberino in 2018.
21 million was chosen in order to involve floating-point arithmetic. The maximum integer that can be represented with 51 bits is just slightly over 2100 trillion.