75 (number)

From Wikipedia, the free encyclopedia

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


Cardinal 75
seventy-five
Ordinal 75th
seventy-fifth
Factorization 3 \cdot 5^2
Divisors 1, 3, 5, 15, 25, 75
Roman numeral LXXV
Binary 1001011
Hexadecimal 4B

[edit] 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.

There are 75 uniform polyhedra.


[edit] In astronomy

Messier object M75, a magnitude 9.5 globular cluster in the constellation Sagittarius

The New General Catalogue object NGC 75, a spiral galaxy in the constellation Pisces

[edit] In other fields

Seventy-five is also: