Properties of the Number 21208

Twenty-One Thousand Two Hundred Eight

Basics

Value: 21207 → 21208 → 21209

Parity: even

Prime: No

Previous Prime: 21193

Next Prime: 21211

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 2 ³ × 11 × 241

Divisors: 1, 2, 4, 8, 11, 22, 44, 88, 241, 482

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001011011000

Octal: 51330

Duodecimal: 10334

Hexadecimal: 52d8

Square: 449779264

Square Root: 145.62966730718023

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

G.f. A(x) satisfies A(x) = 1/∏_k>0 (1-x^k*A(x)). A145268

T(n,k)=Number of -k..k arrays x(0..n-1) of n elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2). A199909

Positive integers m such that π(m³) = π(j³) + π(k³) for some 0 < j <= k < m. A262409

Denominators of continued fraction convergents to sqrt(30). A41049

Denominators of continued fraction convergents to sqrt(750). A42445

Denominators of continued fraction convergents to sqrt(270). A41507

Expansion of (1-x)/(1-2·x-2·x²-2·x³). A77843

Number of -3..3 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2). A199904

Number of primes of the form (x+1)¹¹ - x¹¹ having n digits. A221984

Number of pairs of functions (f,g) on [n] such that fg is an idempotent. A275025