Properties of the Number 21285

Twenty-One Thousand Two Hundred Eighty-Five

Basics

Value: 21284 → 21285 → 21286

Parity: odd

Prime: No

Previous Prime: 21283

Next Prime: 21313

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 5 × 11 × 43

Divisors: 1, 3, 5, 9, 11, 15, 33, 43, 45, 55

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001100100101

Octal: 51445

Duodecimal: 10399

Hexadecimal: 5325

Square: 453051225

Square Root: 145.89379698945393

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) = floor(n*(n-1)*(n-2)/4). A11886

a(n) = 3·binomial(10·n+6,n)/(5·n+3). A234529

Denominator of c(n) = (n²+n+2)/((n+1)*(n+2)*(n+3)). A241269

Denominator of sum of reciprocals of first n pentatope numbers A000332. A118412

a(n) = 32·3ⁿ - 2ⁿ⁺⁵ + 5. A305861

a(n) = 11·n² + 22·n. A67705

a(n) = n*(16·n² - 1). A69975

Number of minimal total dominating sets in the 2 X n king graph. A332392

Upper (3/2)-midsequence of binomial(n,3) and binomial(n,2); see Comments. A390343

Coefficients of replicable function number 15a. A58512