Properties of the Number 21009

Twenty-One Thousand Nine

Basics

Value: 21008 → 21009 → 21010

Parity: odd

Prime: No

Previous Prime: 21001

Next Prime: 21011

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 47 × 149

Divisors: 1, 3, 47, 141, 149, 447, 7003, 21009

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101001000010001

Octal: 51021

Duodecimal: 101A9

Hexadecimal: 5211

Square: 441378081

Square Root: 144.94481708567574

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

Positions of 3's in A234323. A234804

Numbers k such that k*(k+7) is a palindrome. A28564

Numbers n such that A048767(n+1)=A048767(n). A48769

Numbers n such that the decimal equivalent of the binary reflected Gray code representation of n is a palindromic prime. A281382

a(n) = (10n+1)*(10n+9). A1535

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 366", based on the 5-celled von Neumann neighborhood. A268275

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 297", based on the 5-celled von Neumann neighborhood. A271150

T(n,n-3), array T as in A054120. A54121

Smallest number not occurring earlier fitting the repeating pattern "99887766554433221100". A98782

Triangle of coefficients of Laguerre polynomials n!*L_n(x) (rising powers of x). A21009