Properties of the Number -6561

Five Hundred Sixty-One

Basics

Value: -6562 → -6561 → -6560

Parity: odd

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ⁸

Divisors: 1, 3, 9, 27, 81, 243, 729, 2187, 6561

Polygonal

Triangular: No

Square: Yes

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: -1100110100001

Octal: -14641

Duodecimal: -3969

Hexadecimal: -19a1

Square: 43046721

Square Root: 81

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: Yes

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

Expansion of bracket function. A748

a(n) = ∑_{j=0..floor(n/3)} (-1)^j*binomial(n,3·j+1). A57682

a(n) = ∑_{j=0..floor(n/3)} (-1)^j*binomial(n,3·j). A57681

Expansion of (1+2·x)/(1+3·x+3·x²). A123877

a(2n+1)=3a(2n)-3a(2n-1)+2a(2n-2), a(2n+2)=3a(2n+1)-3a(2n), a(0)=a(1)=a(2)=1. A131292

Triangle T(n,k) read by rows: T(n,n) = -1, T(n,0) = 3^{n - 1}, T(n,k) = -3^{n - k - 1}, 1 <= k <= n - 1. A152570

Triangle, T(n, k, q) = e(n, k, q), where e(n, k, q) = ((1 - (-q)^k)/(1+q))*e(n-1, k, q) + (-q)^k-1*e(n-1, k-1, q), e(n, 0, q) = e(n, n, q) = 1, and q = 2, read by rows. A156535

a(n) = 3·a(n-2) for n > 2; a(1) = 3, a(2) = -1. A162852

Numerators to Dirichlet inverse of Euler totient based version of series expansion for x/LambertW(x). A230283

A transform of the Jacobsthal numbers. A103312