Properties of the Number 21811

Twenty-One Thousand Eight Hundred Eleven

Basics

Value: 21810 → 21811 → 21812

Parity: odd

Prime: No

Previous Prime: 21803

Next Prime: 21817

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 17 × 1283

Divisors: 1, 17, 1283, 21811

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101010100110011

Octal: 52463

Duodecimal: 10757

Hexadecimal: 5533

Square: 475719721

Square Root: 147.68547660484427

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 that are the sum of seven fourth powers in exactly six ways. A345828

Number of non-Fibonacci parts in the last section of the set of partitions of n. A144118

T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3, 4, 6, 7 or 8 king-move adjacent elements, with upper left element zero. A300035

Numbers n such that the Collatz iterations for n and n + 1 have the same length (A078417) but do not meet a certain condition. (See comments.) A274410

Number of nX5 0..1 arrays with every element equal to 0, 2, 3, 4, 6, 7 or 8 king-move adjacent elements, with upper left element zero. A300032

a(n) = ∑_j=1..n ∑_i=1..n (j mod i). A367379

Number of n X n 0..1 arrays with every element equal to 0, 2, 3, 4, 6, 7 or 8 king-move adjacent elements, with upper left element zero. A300031

Number of 4Xn 0..1 arrays with every element equal to 0, 1, 3, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. A303527

Decimal expansion of 1/807. A21811