Properties of the Number 21857

Twenty-One Thousand Eight Hundred Fifty-Seven

Basics

Value: 21856 → 21857 → 21858

Parity: odd

Prime: No

Previous Prime: 21851

Next Prime: 21859

Digit Sum: 23

Digital Root: 5

Palindrome: No

Factorization: 11 × 1987

Divisors: 1, 11, 1987, 21857

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010101100001

Octal: 52541

Duodecimal: 10795

Hexadecimal: 5561

Square: 477728449

Square Root: 147.8411309480552

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

Lengths of complete iterations (direct and reverse branches) of the Kolakoski sequence A000002. A249508

Number of partitions of n that include a pair of consecutive integers. A237666

Numerator of ∑_k=1..n-1 1/(k*(n-k))². A304581

a(0) = 1; thereafter a(n) = 10·n² - 5·n + 2. A383466

Define Z(1) = {1}, and Z(n+1) = Z(n) (+) { x+y, with·and y in Z(n) } for any n>0 (where (+) stands for the symmetric difference of two sets). Then a(n) gives the number of elements in Z(n). A263402

Number of walks within N³ (the first octant of Z³) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 1), (0, 1, -1), (1, 0, -1), (1, 1, 1)}. A149689

Companion Pell numbers: a(n) = 2·a(n-1) + a(n-2), a(0) = a(1) = 2. A2203

Decimal expansion of 1/853. A21857