Properties of the Number 21006

Twenty-One Thousand Six

Basics

Value: 21005 → 21006 → 21007

Parity: even

Prime: No

Previous Prime: 21001

Next Prime: 21011

Digit Sum: 9

Digital Root: 9

Palindrome: No

Factorization: 2 × 3 ³ × 389

Divisors: 1, 2, 3, 6, 9, 18, 27, 54, 389, 778

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001000001110

Octal: 51016

Duodecimal: 101A6

Hexadecimal: 520e

Square: 441252036

Square Root: 144.93446795017394

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

Starts of runs of 3 consecutive Niven numbers in base 2 (A049445). A330932

Array read by antidiagonals: A(n,k) is the number of nonnegative integer matrices with k distinct columns and any number of distinct nonzero rows with column sums n and rows in decreasing lexicographic order. A331160

Number of non-isomorphic (i.e., defined up to a rotation and a reflection) maximal independent sets of the n-cycle graph having 2n isomorphic representatives. A127683

Number of distinct sums i³ + j³ + k³ + l³ for 1<=i<=j<=k<=l<=n. A374714

Pisot sequence P(4,11), a(0)=4, a(1)=11, a(n+1) is the nearest integer to a(n)²/a(n-1). Evidently satisfies a(n) = 2·a(n-1)+2·a(n-2). A21006

Array listed by antidiagonals: row m is the numbers k such that prime(i)+k is prime for i from m to j where prime(j+1) = A360228(m). A359843