74 (number)
{{Infobox number
| number = 74
| divisor = 1, 2, 37, 74
}}
74 (seventy-four) is the natural number following 73 and preceding 75.
In mathematics
74 is:
- the twenty-first distinct semiprime{{Cite OEIS|sequencenumber=A001358}} and the eleventh of the form (2.q), where q is a higher prime.
- with an aliquot sum of 40, within an aliquot sequence of three composite numbers (74, 40, 50, 43, 1,0) to the Prime in the 43-aliquot tree.
- a palindromic number in bases 6 (2026) and 36 (2236).
- a nontotient.{{Cite web|url=https://oeis.org/A005277|title=Sloane's A005277 : Nontotients|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-05-29}}
- the number of collections of subsets of {1, 2, 3} that are closed under union and intersection.{{cite OEIS|A306445|Number of collections of subsets of {1, 2, ..., n} that are closed under union and intersection|access-date=2022-05-22}}
- φ(74) = φ(σ(74)).{{cite OEIS|A006872|2=Numbers k such that phi(k) = phi(sigma(k))}}
There are 74 different non-Hamiltonian polyhedra with a minimum number of vertices.{{Cite web|url=https://oeis.org/A007033|title=Sloane's A007033: Non-Hamiltonian polyhedra with n nodes.|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2020-12-11}}