Properties of the Number -1686

Six Hundred Eighty-Six

Basics

Value: -1687 → -1686 → -1685

Parity: even

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 2 × 3 × 281

Divisors: 1, 2, 3, 6, 281, 562, 843, 1686

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: -11010010110

Octal: -3226

Duodecimal: -B86

Hexadecimal: -696

Square: 2842596

Square Root: 41.060930335295616

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

G.f.: 1-q = ∑_k>=0 a(k)*q^k*Faq(k+1,q), where Faq(n,q) is the q-factorial of n. A127926

a(n) = ∑_k<=n A007955(k) * A008683(n-k+1) = ∑_k<=n A007955(k) * μ(n-k+1), where A007955(m) = product of divisors of m. A174942

a(n) = ∑_k=1..n k·floor(n/k); also ∑_k=1..n σ(k) where σ(n) = sum of divisors of n (A000203). A24916

Number of planar rooted trees with n nodes and tricolored end nodes. A47891

Number of partitions of n with no part larger than n/2. Also partitions of n into n/2 or fewer parts. A110618

Number of (1,2,3)-matching compositions of n. A335514

Position of n-th prime in A064413. A64955

Fibonacci sequence beginning 2, 6. A22112

a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = (Lucas numbers). A24319

T(n,k)=Number of (n+1)X(k+1) 0..2 arrays with every element next to itself plus and minus one within the range 0..2 horizontally or antidiagonally, with no adjacent elements equal. A232589