Properties of the Number 20391

Twenty Thousand Three Hundred Ninety-One

Basics

Value: 20390 → 20391 → 20392

Parity: odd

Prime: No

Previous Prime: 20389

Next Prime: 20393

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 3 × 7 × 971

Divisors: 1, 3, 7, 21, 971, 2913, 6797, 20391

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 100111110100111

Octal: 47647

Duodecimal: B973

Hexadecimal: 4fa7

Square: 415792881

Square Root: 142.79705879323984

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

Interprimes (A024675) which are of the form s·prime, s=21. A75296

The bisection A053445(2n+1). A161921

Number of triangular number parts in all partitions of n. A263235

G.f. A(x) satisfies A(x) = 1 + x·A(x)/A(-x·A(x))². A385014

The number of partitions of n which represent Chomp positions with Sprague-Grundy value 10. A284784

Number of partitions of n into exactly 6 different parts with distinct multiplicities. A212117

Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of B(x)^k, where B(x) is the g.f. of A385014. A385018

Triangle read by rows: T(n,m) = ∑_k=0..n StirlingS2(n, k) * Eulerian(n - k + 1, m) *(-1)^{n - k - m} * k!. A174553

Number of closable Motzkin trees. A300125

Numbers k such that the continued fraction for sqrt(k) has period 52. A20391