Properties of the Number 81806

Eighty-One Thousand Eight Hundred Six

Basics

Value: 81805 → 81806 → 81807

Parity: even

Prime: No

Previous Prime: 81799

Next Prime: 81817

Digit Sum: 23

Digital Root: 5

Palindrome: No

Factorization: 2 × 40903

Divisors: 1, 2, 40903, 81806

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10011111110001110

Octal: 237616

Duodecimal: 3B412

Hexadecimal: 13f8e

Square: 6692221636

Square Root: 286.0174819831823

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) = ∑_k=1..n-1 σ(k) * sigma₂(n-k). A374974

Least positive number that can be written using prime factors of n (with repetition) and the operations add and subtract. A81806

G.f. A(x) satisfies: ∑_n>=0 xⁿ*A(x)ⁿ/(1 - x·A(x)ⁿ⁺⁴) = ∑_n>=0 xⁿ*A(x)^2·n/(1 - x·A(x)^5·n+3). A341958