22 (twenty-two) is the
natural number
In mathematics, the natural numbers are the numbers 0, 1, 2, 3, and so on, possibly excluding 0. Some start counting with 0, defining the natural numbers as the non-negative integers , while others start with 1, defining them as the positive in ...
following
21 and preceding
23.
In mathematics
22 is a
semiprime, a
Smith number, and an
Erdős–Woods number.
is a commonly used
approximation of the
irrational number
In mathematics, the irrational numbers are all the real numbers that are not rational numbers. That is, irrational numbers cannot be expressed as the ratio of two integers. When the ratio of lengths of two line segments is an irrational number, ...
, the ratio of the
circumference
In geometry, the circumference () is the perimeter of a circle or ellipse. The circumference is the arc length of the circle, as if it were opened up and straightened out to a line segment. More generally, the perimeter is the curve length arou ...
of a circle to its
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...
.
22 can read as "two twos", which is the only
fixed point of
John Conway's look-and-say function.
The number 22 appears prominently within
sporadic groups. The
Mathieu group M22 is one of 26 sporadic
finite simple groups, defined as the 3-transitive
permutation
In mathematics, a permutation of a set can mean one of two different things:
* an arrangement of its members in a sequence or linear order, or
* the act or process of changing the linear order of an ordered set.
An example of the first mean ...
representation on 22 points. There are also 22
regular complex apeirohedra.
22 has been proven to be a Lychrel number in base 2, since after 4 steps it reaches 10110100, after 8 steps it reaches 1011101000, after 12 steps it reaches 101111010000, and in general after steps it reaches a number consisting of 10, followed by ones, followed by 01, followed by zeros. This number obviously cannot be a palindrome, and none of the other numbers in the sequence are palindromes.
In other fields
*''
Catch-22'' (1961),
Joseph Heller's novel, and its 1970 film adaptation gave rise to the expression of logic "
catch-22".
*
22 equal temperament is a popular
microtonal tuning temperament due to its good approximation of harmonic intervals, especially septimal intervals.
In culture and religion
*22 is a master number in
numerology.
*There are 22 colored properties on a traditional
Monopoly
A monopoly (from Greek language, Greek and ) is a market in which one person or company is the only supplier of a particular good or service. A monopoly is characterized by a lack of economic Competition (economics), competition to produce ...
board.
In weights and measures
*The number of
yard
The yard (symbol: yd) is an English units, English unit of length in both the British imperial units, imperial and US United States customary units, customary systems of measurement equalling 3 foot (unit), feet or 36 inches. Sinc ...
s in a
chain.
In other uses
Twenty-two may also refer to:
*In
French jargon, "22" is used as a phrase to warn of the coming of the police (typically ''"' !"'', in English: "5-0! Cops!")
* In
Spanish lottery and
bingo, 22 is nicknamed after its shape.
See also
*
Catch 22 (disambiguation)
References
External links
*
{{Integers, zero
Integers