Properties of the Number 20640

Twenty Thousand Six Hundred Forty

Basics

Value: 20639 → 20640 → 20641

Parity: even

Prime: No

Previous Prime: 20639

Next Prime: 20641

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 2 ⁵ × 3 × 5 × 43

Divisors: 1, 2, 3, 4, 5, 6, 8, 10, 12, 15

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000010100000

Octal: 50240

Duodecimal: BB40

Hexadecimal: 50a0

Square: 426009600

Square Root: 143.66627996854376

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

Strongly refactorable numbers: numbers n such that if n is divisible by d, it is divisible by the number of divisors of d. A141586

Number of non-equivalent ways to choose two points in an equilateral triangle grid of side n. A227327

Expansion of 1/(1-2·x-2·x²+2·x³). A77937

Numbers n such that there exists an x≠n that makes {n,n,x} an amicable multiset. A259302

T(n,k)=4-level binary fanout graph coloring a rectangular array: number of nXk 0..14 arrays where 0..14 label nodes of a graph with edges 0,1 1,3 3,5 3,6 1,4 4,7 4,8 0,2 2,9 9,11 9,12 2,10 10,13 10,14 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. A223449

Numbers that belong to at least one amicable multiset. A259307

Numbers of the form p⁵*q·r*s where p, q, r, and s are distinct primes. A179704

Number of set partitions of [n] such that for each pair of consecutive blocks (b,b+1) exactly one pair of consecutive numbers (i,i+1) exists with i member of b and i+1 member of b+1. A272064

Expansion of ∏_k>=1 1/((1 - x^2·k-1)^k*(3·k-2)*(1 - x^2·k)^k*(3·k+2)). A294655

Number T(n,k) of plane partitions of n into parts of exactly k sorts; triangle T(n,k), n>=0, 0<=k<=n, read by rows. A319600