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18

Number 18 (eighteen) is an even two-digits composite number and natural number following 17 and preceding 19.

Properties of the number 18

Nominal18
Cardinaleighteen
Ordinal18th
Number of digits2
Sum of digits9
Product of digits8
Number parityEven
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Prime Factorization of 18

Prime factorization2 x 3 x 3
Prime factorization in exponent form2 x 32
Prime factors2, 3
Number of distinct prime factors ω(n)2
Total number of prime factors Ω(n)3
Sum of prime factors5
Product of prime factors6
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Divisors of 18

List of proper divisors 1, 2, 3, 6, 9
List of all dividers1, 2, 3, 6, 9, 18
Number of divisors d(n)6
Sum of all divisors σ(n)39
Aliquot sum 21
18 is an abundant number , because the sum of its proper divisors (21) is greater than itself. Its abundance is 3.
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Prime numbers

Is 18 a prime number?No
Is 18 a semiprime number?No
Is 18 a Chen prime number?No
Is 18 a Mersenne prime number?No
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Sequences

Is 18 a Catalan number?No
Is 18 a Fibonacci number?No
Is 18 a Idoneal number?Yes: I14
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Number theory

Number theory is a branch of pure mathematics devoted primarily to the study of the integers and integer-valued functions.
18 is not a Happy number
18 is a Humble number
18 is not a Münchhausen number
18 is not a Perfect number
18 is not a Perfect square
18 is not a Palindrome
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Numeric Bases of 18

In mathematics, a base or radix of a numeral system is the number of unique digits, including zero, used to represent numbers in that system.
BaseSystemValue
2Binary100102
3Ternary2003
4Quaternary1024
5Quinary335
6Senary306
7Septenary247
8Octal228
9Nonary209
10Decimal18
12Duodecimal1612
16Hexadecimal1216
20Vigesimali20
36Base36i36
60SexagesimalI60
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Mathematical operations

Mathematical operations are actions that are performed on numbers or mathematical expressions to find a numerical result.
Square of 18 (n2)324
Cube of 18 (n3)5832
Square root of 184.2426406871193
Natural Logarithm (ln) of 182.8903717578962
Decimal Logarithm (log) of 181.2552725051033
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Trigonometry

Trigonometry is the study of the relationship between the angles and sides of a triangle.
Sine of 18-0.75098724677168
Cosecant of 18-1.3315805352205
Cosine of 180.66031670824408
Secant of 181.5144248017882
Tangent of 18-1.1373137123377
Cotangent of 18-0.87926487577869
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Number parity

Parity is the property of an integer of whether it is even or odd.

Is 18 an Even Number?

Yes, the number 18 is an even number.

Is 18 an Odd Number?

No
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Ban number

In recreational mathematics, a ban number is a number that does not contain a particular letter when spelled out in English; in other words, the letter is "banned".
The spelling of 18 in words is "eighteen", meaning that:
18 is an aban number (a number without the letter a)
18 is not an eban number (as it contains the letter e)
18 is not an iban number (as it contains the letter i)
18 is an oban number (a number without the letter o)
18 is not a tban number (as it contains the letter t)
18 is an uban number (a number without the letter u)
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Numeral systems

How to write 18 in other number systems?
Bengali numerals১৮
Eastern Arabic numerals١٨
Hieroglyphs numeralsused in Ancient Egypt𓎆𓐁
Khmer numerals១៨
Japanese numerals十八
Roman numeralsXVIII
Thai numerals๑๘
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Translation

How do you say 18 in 38 different languages?
Arabicثمانية عشر
Croatianosamnaest
Czechosmnáct
Danish atten
Dutchachttien
Estonianwuienyi
Faroeseátjan
Filipinolabíng-waló
Finnishkahdeksantoista
Frenchdix-huit
Greekδεκα­οκτώ
Germanachtzehn
Hebrewשמונה עשרה
Hindiअठारह
Hungariantizen­nyolc
Icelandicátján
Indonesiandelapan belas
Italiandiciotto
Japanese十八
Korean십팔
Latvianastoņpadsmit
Lithuanianaštuoniolika
Norwegianatten
Persianهجده
Polishosiemnaście
Portuguesedezoito
Romanianoptsprezece
Russianвосемнадцать
Serbianосамнаест
Slovakosemnásť
Sloveneasemnajst
Spanish dieciocho
Swahilikumi na nane
Swedisharton
Thaiสิบ​แปด
Turkishon sekiz
Ukrainianвісімнадцять
Vietnamesemười tám
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Miscellaneous

Number 18 reversed81
ASCII Code18
Unicode CharacterU+0012
Unix TimestampThu, 01 Jan 1970 00:00:18 +0000
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