Properties of the Number 21890

Twenty-One Thousand Eight Hundred Ninety

Basics

Value: 21889 → 21890 → 21891

Parity: even

Prime: No

Previous Prime: 21881

Next Prime: 21893

Digit Sum: 20

Digital Root: 2

Palindrome: No

Factorization: 2 × 5 × 11 × 199

Divisors: 1, 2, 5, 10, 11, 22, 55, 110, 199, 398

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010110000010

Octal: 52602

Duodecimal: 10802

Hexadecimal: 5582

Square: 479172100

Square Root: 147.9526951427381

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

Number of recursive calls needed to compute the n-th Fibonacci number F(n), starting with F(1) = F(2) = 1. A19274

Length of n-th term in Look and Say sequences A005150 and A007651. A5341

a(n) = 2·Fibonacci(n+2) + ((-1)ⁿ - 3)/2. A66629

Numbers m with C(2·m, m) + prime(m) prime, where C(2·m, m) = (2·m)!/(m!)². A236242

Partial sums of repeated Fibonacci sequence. A94707

Partial sums of F(1) - L(1) + F(2) - L(2) + F(3) - L(3) + ..., where F = A000045 and L = A000032. A355018

Partial sums of L(1) - F(1) + L(2) - F(2) + L(3) - F(3) + ..., where L = A000032 and F = A000045. A355019

Triangle of coefficients of polynomials u(n,x) jointly generated with A209136; see the Formula section. A209135

a(0)=1, a(1)=-2; a(n+2) = a(n+1) + a(n) + (period 3: repeat 3, 1, -1). A226328

Diagonal sums of number triangle A132046. A154327