Properties of the Number 21182

Twenty-One Thousand One Hundred Eighty-Two

Basics

Value: 21181 → 21182 → 21183

Parity: even

Prime: No

Previous Prime: 21179

Next Prime: 21187

Digit Sum: 14

Digital Root: 5

Palindrome: No

Factorization: 2 × 7 × 17 × 89

Divisors: 1, 2, 7, 14, 17, 34, 89, 119, 178, 238

Polygonal

Triangular: No

Square: No

Pentagonal: Yes

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001010111110

Octal: 51276

Duodecimal: 10312

Hexadecimal: 52be

Square: 448677124

Square Root: 145.5403724057349

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

T(n,k)=Number of length n+2 0..k arrays with no three consecutive terms having the sum of any two elements equal to twice the third. A248461

Number of ways to write n as an ordered sum of 7 primes (counting 1 as a prime). A341986

Number of finite regions in a complete bipartite graph where the vertices in the two parts are placed on opposite sides of a parabola at integer·coordinates |x| = 1, 2, ...n. A392426

Smallest k > 0 with gcd(k, rev(k)) = n, where rev(k) is digit reversal of k and with sum of digits of k = n, or 0 if no such k exists. A333666

Expansion of ∏_k>=1 (1 - x^k)¹⁷. A10823

Consider all integer triples (i,j,k), j >= k > 0, with binomial(i+2,3)=j³+k³, ordered by increasing i; sequence gives k values. A54207

a(n) = 1·prime(n) + 2·prime(n-1) + ... + k·prime(n+1-k), where k=floor((n+1)/2) and prime(n) is the n-th prime. A23870

Expansion of ∏_k>=1 ((1 + x)^k + x^k)/((1 + x)^k - x^k). A307521

a(n) = 1·t(n) + 2·t(n-1) + ... + k·t(n+1-k), where k=floor((n+1)/2) and t = A008578 ({1} U primes). A23862

Grow a binary tree using the following rules. Initially there is a single node labeled 1. At each step we add 1 to all labels less than 3. If a node has label 3 and zero or one descendants we add a new descendant labeled 1. Sequence gives sum of all labels at step n. A123015