Properties of the Number 21209

Twenty-One Thousand Two Hundred Nine

Basics

Value: 21208 → 21209 → 21210

Parity: odd

Prime: No

Previous Prime: 21193

Next Prime: 21211

Digit Sum: 14

Digital Root: 5

Palindrome: No

Factorization: 127 × 167

Divisors: 1, 127, 167, 21209

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101001011011001

Octal: 51331

Duodecimal: 10335

Hexadecimal: 52d9

Square: 449821681

Square Root: 145.6331006330635

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

Number of series-reduced trees with n nodes. A14

Triangle read by rows: T(n,k) is the number of unlabeled directed graphs on n nodes with k arcs, k=0..n*(n-1). A52283

Triangle T(n,k) of number of digraphs with a source and a sink on n unlabeled nodes and k arcs, k=0..n*(n-1). A57278

Triangle T(n,k) of number of digraphs with a source on n unlabeled nodes with k arcs, k=0..n*(n-1). A57277

Triangle T(n,k) of number of unilaterally connected digraphs on n unlabeled nodes with k arcs, k=0..n*(n-1). A57270

Triangle T(n,k) of number of digraphs with a quasi-source on n unlabeled nodes and with k arcs, k = 0..n*(n-1). A57279

Position of records in A034693. A194945

Number of ordered triples (w,x,y) with all terms in {1,...,n} and w³ < x³ + y³. A211650

Numbers n such that the least prime of the form 2nk + 1 has a value of k that is larger than the k values for all smaller n. A239727

Irregular triangular array read by rows: T(n,k) is the number of non-isomorphic unlabeled weakly connected digraphs on n nodes and with k arcs. A283753