Properties of the Number 20684

Twenty Thousand Six Hundred Eighty-Four

Basics

Value: 20683 → 20684 → 20685

Parity: even

Prime: No

Previous Prime: 20681

Next Prime: 20693

Digit Sum: 20

Digital Root: 2

Palindrome: No

Factorization: 2 ² × 5171

Divisors: 1, 2, 4, 5171, 10342, 20684

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101000011001100

Octal: 50314

Duodecimal: BB78

Hexadecimal: 50cc

Square: 427827856

Square Root: 143.81933110677437

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

T(n,k)=Number of (n+1)X(k+1) binary arrays with no 2X2 subblock commuting with any of its horizontal and vertical 2X2 subblock neighbors. A187729

a(n) = ∑_k=1..n k²*τ(k), where τ is A000005. A319085

Sum of logarithmic numbers. A2745

For even k >= 4, let f(k) = A066285(k/2) be the minimal difference between primes p and q whose sum is k. Such a k is in the sequence if f(k) > f(m) for all even m with 4 <= m < k. A65978

Number of ways to split an n-cycle into connected subgraphs, all having at least three vertices. A323951

Expansion of ∏_k>=1 (1 - x^8*(2·k-1)) * (1 - x^8·k) / (1 - x^k). A280938

Number of vertices among all distinct circles that can be constructed from a 2·n square grid of points using only a compass. A359859

Number of regions in the planar Farey Ring graph FR(n) defined in A359116, including the regions between the convex hull and the bounding circle. A359117

Let n be even; m = n/2 and p a prime such that p<=m with n-p nonprime. The sequence contains the successive positive maxima of values n with L = primepi(m-1)-primepi(p+1)> 0. A293858

Expansion of e.g.f.: cos(log(1 + sinh(x))). A9020