Properties of the Number 20781

Twenty Thousand Seven Hundred Eighty-One

Basics

Value: 20780 → 20781 → 20782

Parity: odd

Prime: No

Previous Prime: 20773

Next Prime: 20789

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 2309

Divisors: 1, 3, 9, 2309, 6927, 20781

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101000100101101

Octal: 50455

Duodecimal: 10039

Hexadecimal: 512d

Square: 431849961

Square Root: 144.15616532080756

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

Numbers with 3 or more prime factors (with multiplicity) such that every concatenation of their prime factors is prime. A217264

Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 587", based on the 5-celled von Neumann neighborhood. A283142

a(n) is the number of edges formed by n-secting the angles of a nonagon (enneagon). A335783

Decimal expansion of 1/sqrt(24). A20781

Factors k > 0 such that k·x² + 1 produces a new minimum of its Hardy-Littlewood constant. A331946

Number of (n+1)X3 0..2 arrays with every 2X2 subblock trace equal to exactly one or two horizontal and vertical neighbor 2X2 subblock traces. A187133