64,000 cubic feet is how many cubic inches? Is one square foot 12 square inches or 144? Let's say 144. Oh, wait, cubic, so actually 1 cubic foot = 1,728 cubic inches. So 64 cubic feet is 110,592 cubic inches. So 64,000 cubic feet is 110,592,000 cubic inches. Call it 100,000,000 for rounding purposes (I always liked physics profs who let g=10...)

For say 6,000,000,000 people, that is 60 people per cubic inch of gold.

Isn't there a term for one sixtieth of an inch? An archaic term? Then we each get one cubic (archaic term) of gold. Seems small...