Properties of the Number 21084

Twenty-One Thousand Eighty-Four

Basics

Value: 21083 → 21084 → 21085

Parity: even

Prime: No

Previous Prime: 21067

Next Prime: 21089

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 2 ² × 3 × 7 × 251

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

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001001011100

Octal: 51134

Duodecimal: 10250

Hexadecimal: 525c

Square: 444535056

Square Root: 145.20330574749323

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

T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. A300539

Number of almost base-2 palindromic primes (A095743) in range ]2ⁿ,2ⁿ⁺¹]. A95753

Expansion of s(q)⁴ in powers of q where s() is a cubic AGM function. A133078

Triangle read by rows: T(n,k) = arithmetic derivative of (1 + A002110(n) + A002110(k)), 1 <= k <= n, where A002110(n) is the n-th primorial number. A373845

Expansion of 1/sqrt((1-2·x)³ * (1-6·x)). A383950

a(n) = 2·n*(6·n-1). A126964

a(n) = ( 2·n*(2·n² + 11·n + 26) - (-1)ⁿ + 1 )/16. A256666

Expansion of ∏_k>=1 (1 + x^prime(k))/(1 - x^prime(k)). A300413

a(n) = 54·n² - 26·n + 4 (n>=1). A304381

Take apart the sides of each of the integer-sided triangles with perimeter n (at their vertices) and rearrange them orthogonally in 3-space so that their endpoints coincide at a single point. a(n) is the total volume of all rectangular prisms enclosed in this way. A308233