Properties of the Number 84

Eighty-Four

Basics

Value: 83 → 84 → 85

Parity: even

Prime: No

Previous Prime: 83

Next Prime: 89

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 2 ² × 3 × 7

Divisors: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: Yes

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Representations

Binary: 1010100

Octal: 124

Duodecimal: 70

Hexadecimal: 54

Square: 7056

Square Root: 9.16515138991168

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

a(n) = σ(n), the sum of the divisors of n. Also called sigma₁(n). A203

Pascal's triangle read by rows: C(n,k) = binomial(n,k) = n!/(k!*(n-k)!), 0 <= k <= n. A7318

The composite numbers: numbers n of the form x·y for x > 1 and y > 1. A2808

Tetrahedral (or triangular pyramidal) numbers: a(n) = C(n+2,3) = n*(n+1)*(n+2)/6. A292

The nonnegative even numbers: a(n) = 2n. A5843

Numbers that are not squarefree. Numbers that are divisible by a square greater than 1. The complement of A005117. A13929

Read n backwards (referred to as R(n) in many sequences). A4086

Moser-de Bruijn sequence: sums of distinct powers of 4. A695

Triangle of coefficients of Chebyshev's S(n,x) := U(n,x/2) polynomials (exponents in increasing order). A49310

The nonprime numbers: 1 together with the composite numbers, A002808. A18252

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