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Properties of the Number -181

One Hundred Eighty-One

Basics

Value: -182 → -181 → -180

Parity: odd

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 10

Digital Root: 1

Palindrome: Yes

Factorization: 181

Divisors: 1, 181

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: -10110101

Octal: -265

Duodecimal: -131

Hexadecimal: -b5

Square: 32761

Square Root: 13.45362404707371

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) = -a(n-1) - 2·a(n-2). A1607
a(n) = a(n-1) - 2·a(n-2) with a(0) = 2, a(1) = 1. A2249
G.f.: -(1-3·x2-x3)/(1+4·x-4·x3-x4). A97948
E.g.f.: ∏k>=1 cos(xk) [even terms only]. A270663
Expansion of e.g.f.: cos(x·cos(x)) (even powers only). A9015
a(n) = -2·a(n-1) + 3·a(n-2), with a(0)=1, a(1)=2. A84222
Row sums of a number triangle related to the Pell numbers. A110331
Expansion of e.g.f. cos(x/cos(x)) (even powers only). A9118
a(n) = prime(n)-n*τ(n) where τ(n) is the number of divisors of n. A67292
Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f.: exp(∏j=1..n 1/(1+xj) - 1). A294289