Properties of the Number 20721

Twenty Thousand Seven Hundred Twenty-One

Basics

Value: 20720 → 20721 → 20722

Parity: odd

Prime: No

Previous Prime: 20719

Next Prime: 20731

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 6907

Divisors: 1, 3, 6907, 20721

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101000011110001

Octal: 50361

Duodecimal: BBA9

Hexadecimal: 50f1

Square: 429359841

Square Root: 143.94790724425278

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

Expansion of e.g.f. cosh(exp(x)*x). A9121

Numbers k such that (89·10^k-1 + 1)/9 is a depression prime. A82719

Number of partitions p of n such that min(p) < (number of parts of p) < max(p). A325340

Number of n-node unlabeled rooted trees with thinning limbs and root outdegree (branching factor) 2. A244703

Odd numbers k such that φ(k) and cototient(k) have the same prime signature. A280927

Expansion of e.g.f. (exp(x·exp(x)) + exp(x/exp(x)))/2. A195509

Expansion of 1/(1 - ∑_k>=1 x^{k+floor(1/2+sqrt(k}))). A280240

Number of nX4 0..1 arrays with every element unequal to 0, 1, 2, 4, 7 or 8 king-move adjacent elements, with upper left element zero. A316541

Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite MEL = ZSM-11 Nan[AlnSi96-nO192] starting with a T1 atom. A19148

T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 4, 7 or 8 king-move adjacent elements, with upper left element zero. A316545