Properties of the Number 21228

Twenty-One Thousand Two Hundred Twenty-Eight

Basics

Value: 21227 → 21228 → 21229

Parity: even

Prime: No

Previous Prime: 21227

Next Prime: 21247

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 2 ² × 3 × 29 × 61

Divisors: 1, 2, 3, 4, 6, 12, 29, 58, 61, 87

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001011101100

Octal: 51354

Duodecimal: 10350

Hexadecimal: 52ec

Square: 450627984

Square Root: 145.69831845289087

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

E.g.f. A(x) satisfies A(x) = 1 - 2·log(1-x) * A(-log(1-x)). A355098

E.g.f.: -exp(2·x)*LambertW(-x). A277485

Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. -exp(k·x)*LambertW(-x). A294411

(-1)σ sociable number of order 2: (-1)σ((-1)σ(x))=x, but (-1)σ(x)<>x, where if x=Product p(i)^r(i) then (-1)σ(x)=Product (-1+Sum p(i)^s(i), s(i)=1 to r(i)); (-1)σ(1)=1. A51152

Row sums of triangle A119935 (numerator triangle for certain rationals). A119934

a(n) is the smallest number k such that d(1)*1! + d(2)*2! + ... + d(p)*p! = n², where d(i) are the decimal digits of k. A198095

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 581", based on the 5-celled von Neumann neighborhood. A273071

Numbers k such that 129·2^k-1 is prime. A50590

Decimal expansion of 1/224. A21228