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# 28

Number 28 (twenty-eight) is an even two-digits composite number and natural number following 27 and preceding 29.

## Properties of the number 28

 Nominal 28 Cardinal twenty-eight Ordinal 28th Number of digits 2 Sum of digits 10 Product of digits 16 Number parity Even
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## Prime Factorization of 28

 Prime factorization 2 x 2 x 7 Prime factorization in exponent form 22 x 7 Prime factors 2, 7 Number of distinct prime factors ω(n) 2 Total number of prime factors Ω(n) 3 Sum of prime factors 9 Product of prime factors 14
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## Divisors of 28

 List of proper divisors 1, 2, 4, 7, 14 List of all dividers 1, 2, 4, 7, 14, 28 Number of divisors d(n) 6 Sum of all divisors σ(n) 56 Aliquot sum 28 28 is a perfect number, since it is equal to the sum of its proper divisors.
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## Prime numbers

 Is 28 a prime number? No Is 28 a semiprime number? No Is 28 a Chen prime number? No Is 28 a Mersenne prime number? No
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## Sequences

 Is 28 a Catalan number? No Is 28 a Fibonacci number? No Is 28 a Idoneal number? Yes: I19
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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.
 28 is a Happy number 28 is a Humble number 28 is not a Münchhausen number 28 is a Perfect number 28 is not a Perfect square 28 is not a Palindrome
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## Numeric Bases of 28

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
2Binary111002
3Ternary10013
4Quaternary1304
5Quinary1035
6Senary446
7Septenary407
8Octal348
9Nonary319
10Decimal28
12Duodecimal2412
20Vigesimal1820
36Base36s36
60SexagesimalS60
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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 28 (n2) 784 Cube of 28 (n3) 21952 Square root of 28 5.2915 Natural Logarithm (ln) of 28 3.3322 Decimal Logarithm (log) of 28 1.44716
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## Trigonometry

Trigonometry is the study of the relationship between the angles and sides of a triangle.
 Sine of 28 0.270906 Cosecant of 28 3.69132 Cosine of 28 -0.962606 Secant of 28 -1.03885 Tangent of 28 -0.28143 Cotangent of 28 -3.55329
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## Number parity

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

### Is 28 an Even Number?

Yes, the number 28 is an even number.

### Is 28 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 28 in words is "twenty-eight", meaning that: 28 is an aban number (a number without the letter a) 28 is not an eban number (as it contains the letter e) 28 is not an iban number (as it contains the letter i) 28 is an oban number (a number without the letter o) 28 is not a tban number (as it contains the letter t) 28 is an uban number (a number without the letter u)
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## Numeral systems

How to write 28 in other number systems?
 Bengali numerals ২৮ Eastern Arabic numerals ٢٨ Hieroglyphs numeralsused in Ancient Egypt 𓎇𓐁 Khmer numerals ២៨ Japanese numerals 二十八 Roman numerals XXVIII Thai numerals ๒๘
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## Translation

How do you say 28 in 38 different languages?
 Arabic ثمانية و عشرون Croatian dvadeset i osam Czech dvacet osm Danish otte og tyve Dutch achtentwintig Estonian blaeve vɔ enyi Faroese tjúgo­átta Filipino dalawáng pû’t waló Finnish kaksi­kymmentä­kahdeksan French vingt-huit Greek είκοσι οκτώ German acht­und­zwanzig Hebrew עשרים ושמונה Hindi अट्ठाईस Hungarian huszon­nyolc Icelandic tuttugu og átta Indonesian dua puluh delapan Italian ventotto Japanese 二十八 Korean 이십팔 Latvian divdesmit astoņi Lithuanian dvidešimt aštuoni Norwegian tjue­åtte Persian بیست و هشت Polish dwadzieścia osiem Portuguese vinte e oito Romanian douăzeci şi opt Russian двадцать восемь Serbian двадесет и осам Slovak dvadsať­osem Slovene dvaset osem Spanish veintiocho Swahili ishirini na nane Swedish tjugoåtta Thai ยี่​สิบ​แปด Turkish yirmi sekiz Ukrainian двадцять вісім Vietnamese hai mươi tám
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## Miscellaneous

 Number 28 reversed 82 ASCII Code 28 Unicode Character U+001C Unix Timestamp Thu, 01 Jan 1970 00:00:28 +0000
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