(268,581 sq mi) x (2,747,840 sq ft/sq mi) divided by (6,525,170,264 persons) = 1147.5 sq ft per person in the world, which is the equivalent of a square that is 33 ft 10.5 inches on a side.
Not much space, but it is a surprising result nonetheless.
Also consider the effects of skyscraper technology, building above ground and below, double decker highways with robot cars forming compressed virtual trains. Technology changes everything. The cliche "buy land, they aren't making any more" isn't really true, we're building more land all the time.
Wow, Singapore only has 1635.9 sq ft per person now. A cruise ship only uses 37 square feet of ocean per person, no square feet of land at all.