75

75 (seventy-five) is the natural number following 74 and preceding 76.

← 74 76 → 75
← 70 71 72 73 74 75 76 77 78 79 → List of numbers — Integers 0 10 20 30 40 50 60 70 80 90 →
Cardinal	seventy-five
Ordinal	75th (seventy-fifth)
Numeral system	75
Factorization
Divisors	1, 3, 5, 15, 25, 75
Roman numeral	LXXV
Binary	10010112
Octal	1138
Duodecimal	6312
Hexadecimal	4B16

In mathematics

As the sum of the first five pentagonal numbers, seventy-five is a pentagonal pyramidal number. It is also an enneagonal number.

It is also a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 7, 5, 12, 17, 29, 46, 75... But there is no integer that added up to its own digits adds up to 75, hence 75 is a self number.

Excluding the infinite sets, there are 75 uniform polyhedra (or 76 if edges are allowed to coincide).

In other fields

Seventy-five is also:

• Diamond anniversary^{[citation needed]}
• The atomic number of rhenium
• The age limit for Canadian senators^{[citation needed]}
• Municipal Okrug 75, a municipal okrug of Frunzensky District of Saint Petersburg, Russia
• A common name for the Canon de 75 modèle 1897, a French World War 1 gun
• The departement number of the city of Paris