Properties of the Number -861

Eight Hundred Sixty-One

Basics

Value: -862 → -861 → -860

Parity: odd

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 3 × 7 × 41

Divisors: 1, 3, 7, 21, 41, 123, 287, 861

Polygonal

Triangular: Yes

Square: No

Pentagonal: No

Hexagonal: Yes

Heptagonal: No

Tetrahedral: No

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Representations

Binary: -1101011101

Octal: -1535

Duodecimal: -5B9

Hexadecimal: -35d

Square: 741321

Square Root: 29.34280150224242

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

Expansion of 1/(1 + x - x³ - x⁴ - x⁸ - x¹² - x¹³ - x¹⁷ - x²¹ - x²² - x²⁶ - x³⁰ - x³¹ + x³³ + x³⁴). A173908

Alternating sum of squares to n. A89594

Sequence is {a(3,n)}, where a(m,n) is defined at sequence A110665. A110668

Triangle read by rows: row n gives coefficients C(n,j) for a Sheffer sequence (binomial-type) with lowering operator (D-1)/2 + T{ (1/2) * exp[(D-1)/2] } where T(x) is Cayley's Tree function. A135494

Alternating sum of hexagonal pyramidal numbers. A266677

Triangle T, read by rows, equal to the matrix product T = H·C*H, where H is the self-inverse triangle A118433 and C is Pascal's triangle. A118438

Exponential Riordan array (e^-x(1+x),x). A122833

a(n) = μ(n) * A000217(n). A125287

Values of n such that L(3) and N(3) are both prime, where L(k) = (n²+n+1)*2^2·k + (2·n+1)*2^k + 1, N(k) = (n²+n+1)*2^k + n. A226923

a(1) = 1; a(n) = -(1/2) * ∑_{d∣n, d > 1} d * (d + 1) * a(n/d). A334879