Properties of the Number 19840

Nineteen Thousand Eight Hundred Forty

Basics

Value: 19839 → 19840 → 19841

Parity: even

Prime: No

Previous Prime: 19819

Next Prime: 19841

Digit Sum: 22

Digital Root: 4

Palindrome: No

Factorization: 2 ⁷ × 5 × 31

Divisors: 1, 2, 4, 5, 8, 10, 16, 20, 31, 32

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 100110110000000

Octal: 46600

Duodecimal: B594

Hexadecimal: 4d80

Square: 393625600

Square Root: 140.85453489327207

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

a(0) = 0; for n>0, a(n) = maximal number of regions into which space can be divided by n spheres. A46127

Numbers k such that σ (x) = k has exactly 11 solutions. A60678

Nonnegative values·of solutions (x, y) to the Diophantine equation x²+(x+89)² = y². A129298

T(n,k)=Number of (n+4)X(k+4) binary arrays with every 5X5 subblock commuting with each horizontal and vertical neighbor 5X5 subblock. A186609

Numbers with prime signature {7,1,1}, i.e., of form p⁷*q·r with p, q and r distinct primes. A179696

T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. A320371

G.f. A(x) is defined as the limit A(x) = lim_n->oo F(n)^{1/2^(n-1}) where F(n) is defined by F(n) = F(n-1)² + (2·x)^2ⁿ-1 for n >= 1 with F(0) = 1. A101189

Janet periodic table of the elements and structured hexagonal diamond numbers. a(n) = A166911(2·n) + A166911(2·n+1). A167471

a(n) = 2·n*(n+1)*(n+2)/3. A210440

a(n) = 4·n*(21·n - 26). A263229