81
Number 81 (eighty-one) is an odd two-digits composite number and natural number following 80 and preceding 82.
| Nominal | 81 |
| Cardinal | eighty-one |
| Ordinal | 81st |
| Number of digits | 2 |
| Sum of digits | 9 |
| Product of digits | 8 |
| Number parity | Odd |
Calculation was done in 0.0000369549 seconds
| Prime factorization | 3 x 3 x 3 x 3 |
| Prime factorization in exponent form | 34 |
| Prime factors | 3 |
| Number of distinct prime factors ω(n) | 1 |
| Total number of prime factors Ω(n) | 4 |
| Sum of prime factors | 3 |
| Product of prime factors | 3 |
Calculation was done in 0.0000100136 seconds
| List of proper divisors | 1, 3, 9, 27 |
| List of all dividers | 1, 3, 9, 27, 81 |
| Number of divisors d(n) | 5 |
| Sum of all divisors σ(n) | 121 |
| Aliquot sum | 40 |
| 81 is a deficient number , since it is larger than the sum of its proper divisors (40). Its deficiency is 41. |
Calculation was done in 0.0000250340 seconds
| Is 81 a prime number? | No |
| Is 81 a semiprime number? | No |
| Is 81 a Chen prime number? | No |
| Is 81 a Mersenne prime number? | No |
Calculation was done in 0.0000159740 seconds
| Is 81 a Catalan number? | No |
| Is 81 a Fibonacci number? | No |
| Is 81 a Idoneal number? | No |
Calculation was done in 0.0000050068 seconds
| 81 is not a Happy number |
| 81 is a Humble number |
| 81 is not a Münchhausen number |
| 81 is not a Perfect number |
| 81 is a Perfect square |
| 81 is not a Palindrome |
Calculation was done in 0.0053369999 seconds
| Base | System | Value |
|---|
| 2 | Binary | 10100012 |
| 3 | Ternary | 100003 |
| 4 | Quaternary | 11014 |
| 5 | Quinary | 3115 |
| 6 | Senary | 2136 |
| 7 | Septenary | 1447 |
| 8 | Octal | 1218 |
| 9 | Nonary | 1009 |
| 10 | Decimal | 81 |
| 12 | Duodecimal | 6912 |
| 16 | Hexadecimal | 5116 |
| 20 | Vigesimal | 4120 |
| 36 | Base36 | 2936 |
| 60 | Sexagesimal | 1L60 |
Calculation was done in 0.0000188351 seconds
| Square of 81 (n2) | 6561 |
| Cube of 81 (n3) | 531441 |
| Square root of 81 | 9 |
| Natural Logarithm (ln) of 81 | 4.3944491546724 |
| Decimal Logarithm (log) of 81 | 1.9084850188786 |
Calculation was done in 0.0000050068 seconds
| Sine of 81 | -0.62988799427445 |
| Cosecant of 81 | -1.5875838388567 |
| Cosine of 81 | 0.77668598202163 |
| Secant of 81 | 1.2875216279778 |
| Tangent of 81 | -0.81099441583189 |
| Cotangent of 81 | -1.2330541129241 |
Calculation was done in 0.0000119209 seconds
Is 81 an Odd Number?
Yes, the number 81 is an odd number.
Total number of all odd numbers from 1 to 81 is
41Sum of all the odd numbers from 1 to 81 are
1681The sum of all odd numbers is a perfect square: 1681 = 41
An odd number is any integer (a whole number) that cannot be divided by 2 evenly. Odd numbers are the opposite of even numbers.Previous odd number is
79
Calculation was done in 0.0000069141 seconds
| The spelling of 81 in words is "eighty-one", meaning that: |
| 81 is an aban number (a number without the letter a) |
| 81 is not an eban number (as it contains the letter e) |
| 81 is not an iban number (as it contains the letter i) |
| 81 is not an oban number (as it contains the letter o) |
| 81 is not a tban number (as it contains the letter t) |
| 81 is an uban number (a number without the letter u) |
Calculation was done in 0.0000030994 seconds
| Bengali numerals | ৮১ |
| Eastern Arabic numerals | ٨١ |
| Hieroglyphs numeralsused in Ancient Egypt | 𓎍𓏺 |
| Khmer numerals | ៨១ |
| Japanese numerals | 八十一 |
| Roman numerals | LXXXI |
| Thai numerals | ๘๑ |
Calculation was done in 0.0001060963 seconds
| Arabic | واحد و ثمانون |
| Croatian | osamdeset i jedan |
| Czech | osmdesát jeden |
| Danish | en og firs |
| Dutch | éénentachtig |
| Estonian | blaenyi vɔ ɖekɛ |
| Faroese | áttatiein |
| Filipino | walóng pû’t isá |
| Finnish | kahdeksankymmentäyksi |
| French | quatre-vingt-un |
| Greek | ογδόντα ένα |
| German | einundachtzig |
| Hebrew | שמונים ואחת |
| Hindi | इक्यासी |
| Hungarian | nyolcvanegy |
| Icelandic | áttatíu og einn |
| Indonesian | delapan puluh satu |
| Italian | ottantuno |
| Japanese | 八十一 |
| Korean | 팔십일 |
| Latvian | astoņdesmit viens |
| Lithuanian | aštuoniasdešimt vienas |
| Norwegian | åttién |
| Persian | هشتاد و یک |
| Polish | osiemdziesiąt jeden |
| Portuguese | oitenta e um |
| Romanian | optzeci şi unu |
| Russian | восемьдесят один |
| Serbian | осамдесет и један |
| Slovak | osemdesiatjeden |
| Slovene | osemdeset ena |
| Spanish | ochenta y uno |
| Swahili | themanini na moja |
| Swedish | åttioen |
| Thai | แปดสิบเอ็ด |
| Turkish | seksen bir |
| Ukrainian | вісімдесят один |
| Vietnamese | tám mươi mốt |
Calculation was done in 0.0138459206 seconds
| Number 81 reversed | 18 |
| ASCII Code | 81 | Q |
| Unicode Character | U+0051 | Q |
| Unix Timestamp | Thu, 01 Jan 1970 00:01:21 +0000 |
Calculation was done in 0.0000441074 seconds
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