Properties of the Number 1806

One Thousand Eight Hundred Six

Basics

Value: 1805 → 1806 → 1807

Parity: even

Prime: No

Previous Prime: 1801

Next Prime: 1811

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 2 × 3 × 7 × 43

Divisors: 1, 2, 3, 6, 7, 14, 21, 42, 43, 86

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 11100001110

Octal: 3416

Duodecimal: 1066

Hexadecimal: 70e

Square: 3261636

Square Root: 42.49705872175156

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

Oblong (or promic, pronic, or heteromecic) numbers: a(n) = n*(n+1). A2378

Denominator of Bernoulli number B_n. A27642

Large Schröder numbers (or large Schroeder numbers, or big Schroeder numbers). A6318

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

Triangle of numbers T(n,k) = k!*Stirling2(n,k) read by rows (n >= 1, 1 <= k <= n). A19538

Denominators of Bernoulli numbers B_2n. A2445

a(n) = n*φ(n). A2618

Triangle of numbers T(n,k) = k!*Stirling2(n,k) = A000142(k)*A048993(n,k) read by rows, T(n, k) for 0 <= k <= n. A131689

Products of exactly four distinct primes. A46386

a(n) = 2·n*(2·n+1). A2943