Properties of the Number -91

Ninety-One

Basics

Value: -92 → -91 → -90

Parity: odd

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 10

Digital Root: 1

Palindrome: No

Factorization: 7 × 13

Divisors: 1, 7, 13, 91

Polygonal

Triangular: Yes

Square: No

Pentagonal: No

Hexagonal: Yes

Heptagonal: No

Tetrahedral: No

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Representations

Binary: -1011011

Octal: -133

Duodecimal: -77

Hexadecimal: -5b

Square: 8281

Square Root: 9.539392014169456

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

Monic integer version of Chebyshev T-polynomials (increasing powers). A127672

Lucas and Lehmer numbers with parameters (1 +- sqrt(-7))/2. A107920

Riordan array (1/(1-x), x/(1+x)). A112468

Imaginary part of the sum of divisors function σ(n) generalized for Gaussian integers. A103229

Signed denominators of Leibniz series for π/4. A157142

Rectangular array: A(n,k) = ∑_j=0..k (-1)^floor(j/2)*binomial(k-floor((j+1)/2), floor(j/2))*(-n)^k-j, n >= 1, k >= 0, read by antidiagonals. A299045

Generalized Stirling number triangle of first kind read by rows: T(n, k) = [x^k] ∏_m=1..n (x - m - r), with r = 9. A51523

Alternating sum of squares to n. A89594

a(n+1) = -∑_d∣n a(d), a(1) = 1. A281487

Irregular triangle read by rows of the initial floor(n/2) + 1 coefficients of 1/C(x)ⁿ, where C(x) is the g.f. of the Catalan sequence (A000108). A132460