128 bit
Click on the red underlined text to get to the source
...
IPv6 addresses, being 128 bits long, need 32 characters to write in
the general case, if standard hex representation, is used, plus more
for any punctuation inserted (typically about another 7 characters,
...
... The new standard way of writing IPv6 addresses is to treat them as a
128 bit integer, encode that in base 85 notation, then encode that
using 85 ASCII characters ...
...
In decimal, considered as a 128 bit number, that is
21932261930451111902915077091070067066.
...
...
Many current processors do not find 128 bit integer arithmetic, as
required for this technique, a trivial operation. This is not
...