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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

 Nominal 18 Cardinal eighteen Ordinal 18th Number of digits 2 Sum of digits 9 Product of digits 8 Number parity Even
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## Prime Factorization of 18

 Prime factorization 2 x 3 x 3 Prime factorization in exponent form 2 x 32 Prime factors 2, 3 Number of distinct prime factors ω(n) 2 Total number of prime factors Ω(n) 3 Sum of prime factors 5 Product of prime factors 6
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## Divisors of 18

 List of proper divisors 1, 2, 3, 6, 9 List of all dividers 1, 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
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 18 4.24264 Natural Logarithm (ln) of 18 2.89037 Decimal Logarithm (log) of 18 1.25527
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## Trigonometry

Trigonometry is the study of the relationship between the angles and sides of a triangle.
 Sine of 18 -0.750987 Cosecant of 18 -1.33158 Cosine of 18 0.660317 Secant of 18 1.51442 Tangent of 18 -1.13731 Cotangent of 18 -0.879265
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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 numerals ১৮ Eastern Arabic numerals ١٨ Hieroglyphs numeralsused in Ancient Egypt 𓎆𓐁 Khmer numerals ១៨ Japanese numerals 十八 Roman numerals XVIII Thai numerals ๑๘
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## Translation

How do you say 18 in 38 different languages?
 Arabic ثمانية عشر Croatian osamnaest Czech osmnáct Danish atten Dutch achttien Estonian wuienyi Faroese átjan Filipino labíng-waló Finnish kahdeksantoista French dix-huit Greek δεκα­οκτώ German achtzehn Hebrew שמונה עשרה Hindi अठारह Hungarian tizen­nyolc Icelandic átján Indonesian delapan belas Italian diciotto Japanese 十八 Korean 십팔 Latvian astoņpadsmit Lithuanian aštuoniolika Norwegian atten Persian هجده Polish osiemnaście Portuguese dezoito Romanian optsprezece Russian восемнадцать Serbian осамнаест Slovak osemnásť Slovene asemnajst Spanish dieciocho Swahili kumi na nane Swedish arton Thai สิบ​แปด Turkish on sekiz Ukrainian вісімнадцять Vietnamese mười tám
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## Miscellaneous

 Number 18 reversed 81 ASCII Code 18  Unicode Character U+0012  Unix Timestamp Thu, 01 Jan 1970 00:00:18 +0000
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