Properties of the Number 20999

Twenty Thousand Nine Hundred Ninety-Nine

Basics

Value: 20998 → 20999 → 21000

Parity: odd

Prime: No

Previous Prime: 20983

Next Prime: 21001

Digit Sum: 29

Digital Root: 2

Palindrome: No

Factorization: 11 × 23 × 83

Divisors: 1, 11, 23, 83, 253, 913, 1909, 20999

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001000000111

Octal: 51007

Duodecimal: 1019B

Hexadecimal: 5207

Square: 440958001

Square Root: 144.91031709302138

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

Lucas-Carmichael numbers: squarefree composite numbers k such that p | k => p+1 | k+1. A6972

Lucas-Carmichael numbers with 3 prime factors. A216925

Composite numbers k that divide Fibonacci(k+1). A69107

Odd composite integers m such that F(m)² == 1 (mod m), where F(m) is the m-th Fibonacci number. A337231

Numbers k such that gcd(3k,8^k+1) = 3 but k does not divide the numerator of B(2k) (the Bernoulli numbers). A70193

a(n) = prime(n)*prime(n+1) + prime(n) + prime(n+1). A126199

Composite numbers k that divide Fibonacci(k+1) or Fibonacci(k-1). A182554

Odd composite integers m such that A005248(m) == 3 (mod m). A335672

Numbers k that divide Fibonacci(k+1) but do not divide Fibonacci(k) + 1. A94412

a(n) = n*(n+1)*(n² + 21·n + 50)/24. A101854