| ||||
---|---|---|---|---|
Cardinal | eighty-four | |||
Ordinal | 84th (eighty-fourth) | |||
Factorization | 22 × 3 × 7 | |||
Divisors | 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84 | |||
Greek numeral | ΠΔ´ | |||
Roman numeral | LXXXIV | |||
Binary | 10101002 | |||
Ternary | 100103 | |||
Senary | 2206 | |||
Octal | 1248 | |||
Duodecimal | 7012 | |||
Hexadecimal | 5416 |
84 (eighty-four) is the natural number following 83 and preceding 85.
84 is a semiperfect number, [1] being thrice a perfect number, and the sum of the sixth pair of twin primes . [2] It is the number of four-digit perfect powers in decimal. [3]
It is the third (or second) dodecahedral number, [4] and the sum of the first seven triangular numbers (1, 3, 6, 10, 15, 21, 28), which makes it the seventh tetrahedral number. [5]
The twenty-second unique prime in decimal, with notably different digits than its preceding (and known following) terms in the same sequence, contains a total of 84 digits. [6]
A hepteract is a seven-dimensional hypercube with 84 penteract 5-faces. [7]
84 is the limit superior of the largest finite subgroup of the mapping class group of a genus surface divided by .[ citation needed ]
Under Hurwitz's automorphisms theorem, a smooth connected Riemann surface of genus will contain an automorphism group whose order is classically bound to . [8]
84 is the thirtieth and largest for which the cyclotomic field has class number (or unique factorization), preceding 60 (that is the composite index of 84), [9] and 48. [10] [11]
There are 84 zero divisors in the 16-dimensional sedenions . [12]
Eighty-four is also:
2 (two) is a number, numeral and digit. It is the natural number following 1 and preceding 3. It is the smallest and only even prime number.
10 (ten) is the even natural number following 9 and preceding 11. Ten is the base of the decimal numeral system, the most common system of denoting numbers in both spoken and written language.
21 (twenty-one) is the natural number following 20 and preceding 22.
33 (thirty-three) is the natural number following 32 and preceding 34.
In number theory, an abundant number or excessive number is a positive integer for which the sum of its proper divisors is greater than the number. The integer 12 is the first abundant number. Its proper divisors are 1, 2, 3, 4 and 6 for a total of 16. The amount by which the sum exceeds the number is the abundance. The number 12 has an abundance of 4, for example.
90 (ninety) is the natural number following 89 and preceding 91.
27 is the natural number following 26 and preceding 28.
48 (forty-eight) is the natural number following 47 and preceding 49. It is four dozens or one third of a gross.
104 is the natural number following 103 and preceding 105.
100 or one hundred is the natural number following 99 and preceding 101.
144 is the natural number following 143 and preceding 145.
132 is the natural number following 131 and preceding 133.
135 is the natural number following 134 and preceding 136.
168 is the natural number following 167 and preceding 169.
1728 is the natural number following 1727 and preceding 1729. It is a dozen gross, or one great gross. It is also the number of cubic inches in a cubic foot.
240 is the natural number following 239 and preceding 241.
5 (five) is a number, numeral and digit. It is the natural number, and cardinal number, following 4 and preceding 6, and is a prime number.
744 is the natural number following 743 and preceding 745.
888 is the natural number following 887 and preceding 889.
14 (fourteen) is a natural number following 13 and preceding 15.