Properties of the Number 21018

Twenty-One Thousand Eighteen

Basics

Value: 21017 → 21018 → 21019

Parity: even

Prime: No

Previous Prime: 21017

Next Prime: 21019

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 2 × 3 × 31 × 113

Divisors: 1, 2, 3, 6, 31, 62, 93, 113, 186, 226

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001000011010

Octal: 51032

Duodecimal: 101B6

Hexadecimal: 521a

Square: 441756324

Square Root: 144.97586005952854

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

Array T(n,k) read by antidiagonals: T(n,k) is the number of [n,k]-triangulations in the plane, n >= 0, k >= 0. A169808

Numbers on the square spiral board that are enclosed by four primes. A341542

Sequence of the "Natural Jewels": a natural jewel is a number that is totally enclosed by prime numbers in a version of Ulam Spiral. A172294

Number of entries in the eighth cycles of all permutations of [n]. A285236

[ (4th elementary symmetric function of S(n))/(2nd elementary symmetric of S(n)) ], where S(n) = {3,4, ..., n+5}. A24194

Index of first occurrence of n in A154404. A154952

Numbers n such that n is the average of four consecutive primes n-5, n-1, n+1 and n+5. A258088

Numbers k > 0 such that either 3·k+4, k-2, k+2, n+k or 3·k+5, k-1, k+1, k+5 are all primes. A290130

Number of Schroeder paths of semilength n up to reversal. A378939

Numbers k such that A335579(k) is divisible by at least one of the composites between prime(k) and prime(k+1). A335580