340,282,366,920,938,463,463,374,607,431,768,211,456 IPv6
4,294,967,296 IPv4
18,446,744,073,709,551,616 for a /64
Times
4,294,967,296
=
79,228,162,514,264,337,593,543,950,336
340,282,366,920,938,463,463,374,607,431,768,211,456
take
79,228,162,514,264,337,593,543,950,336
=
So it fits in that big number if everyone had a /64 but really do you need that many like /96 is the size of the IPv4 now how many more IP's do you want?.