Properties of the Number 21672

Twenty-One Thousand Six Hundred Seventy-Two

Basics

Value: 21671 → 21672 → 21673

Parity: even

Prime: No

Previous Prime: 21661

Next Prime: 21673

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 2 ³ × 3 ² × 7 × 43

Divisors: 1, 2, 3, 4, 6, 7, 8, 9, 12, 14

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010010101000

Octal: 52250

Duodecimal: 10660

Hexadecimal: 54a8

Square: 469675584

Square Root: 147.21412975662358

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

Triangle read by rows, Xⁿ * [1,0,0,0,...]; where X = a tridiagonal matrix with (1,2,3,...) in the main diagonal and (1,1,1,...) in the sub and subsubdiagonals. A140735

Number of achiral color patterns (set partitions) for a row or loop of length n using exactly 5 colors (sets). A304975

Primorial deflation of the n-th colossally abundant number: the unique integer k such that A108951(k) = A004490(n). A342012

Riordan array (1/sqrt(1-6x+5x²),(1-3x-sqrt(1-6x+5x²))/(2x)). A110165

a(n) = [xⁿ] G(x)ⁿ, where G(x) = ∏_{k >= 1} (1 + x^k)^k² is the g.f. of A027998. A380291

a(n) = ∑_k=0..n binomial(n+3,k+3) * binomial(2·k+6,k+6). A387239

a(n) = 12·n*(n-1). A64200

Triangle, read by rows, of trinomial coefficients arranged so that there are n+1 terms in row n by setting T(n,k) equal to the coefficient of z^k in (1 + 3·z + z²)^n-[k/2], for n>=k>=0, where [k/2] is the integer floor of k/2. A99512

a(n) = 729·n - 198. A156772

Number of (w,x,y,z) with all terms in {1,...,n} and median<=mean. A212134