Properties of the Number 20806

Twenty Thousand Eight Hundred Six

Basics

Value: 20805 → 20806 → 20807

Parity: even

Prime: No

Previous Prime: 20789

Next Prime: 20807

Digit Sum: 16

Digital Root: 7

Palindrome: No

Factorization: 2 × 101 × 103

Divisors: 1, 2, 101, 103, 202, 206, 10403, 20806

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000101000110

Octal: 50506

Duodecimal: 1005A

Hexadecimal: 5146

Square: 432889636

Square Root: 144.24285077604367

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

Numbers of the form 2·p*q where (p,q) is a twin prime pair. A71142

Numbers n such that sum of distinct primes dividing n is divisible by the largest prime dividing n. Also n is neither a prime, nor a true power of prime and n is squarefree. Squarefree solutions of A071140. A71141

a(n) = 2·prime(n)*prime(n+1). A69486

Squarefree numbers which yield zero when their prime factors are xored together. A235488

Denominators of continued fraction convergents to sqrt(650). A42249

Squarefree numbers k such that the largest prime factor of k is equal to the sum of the other prime factors of k. A71312

Nonsquares with A072594(n) = 0. A72596

Numbers k = p·q*r (p, q, r prime) congruent to 0 mod p+q+r. A160394

Number of 2 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 neighboring 1s. A297432

Numbers k such that if P = 10·k²+1, then P, P+6, P+12 and P+18 are all primes. A92446