75 (seventy-five) is the natural number following 74 and preceding 76.
75 is a self number because there is no integer that added up to its own digits adds up to 75.
[2][3] It is also the fourth ordered Bell number, and a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 7, 5, 12, 17, 29, 46, 75...[4] 75 is the count of the number of weak orderings on a set of four items.
[5] Excluding the infinite sets, there are 75 uniform polyhedra in the third dimension, which incorporate star polyhedra as well.
Inclusive of 7 families of prisms and antiprisms, there are also 75 uniform compound polyhedra.