Properties of the Number 16821

Sixteen Thousand Eight Hundred Twenty-One

Basics

Value: 16820 → 16821 → 16822

Parity: odd

Prime: No

Previous Prime: 16811

Next Prime: 16823

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ³ × 7 × 89

Divisors: 1, 3, 7, 9, 21, 27, 63, 89, 189, 267

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 100000110110101

Octal: 40665

Duodecimal: 9899

Hexadecimal: 41b5

Square: 282946041

Square Root: 129.69579792730372

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

G.f. satisfies: A(x) = x + A(x²/(1-x)²). A119685

a(n) = 20·n² + 1. A158493

a(0) = 12, after which, if a(n-1) = ∏_{k >= 1} (p_k)^c_k, then a(n) = (1/2) * (1 + ∏_{k >= 1} (p_k+1)^c_k), where p_k indicates the k-th prime, A000040(k). A246342

a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 3, where m = 2·n - 2 - 2^p+1 and p is the unique integer such that 2^p < n-1 <= 2^p+1, starting with a(1) = 1 and a(2) = 3. A49919

Triangle T(n,k) giving number of 4 X k polyominoes with n cells (n >= 4, 1<=k<=n-3). A59684

a(n) = 841·n + 1. A158404

Potential magic constants of 9 X 9 magic squares composed of consecutive primes. A191679

Group the natural numbers such that the first group is (1) then (2),(3),(4,5),(6,7,8),... with the n-th group containing F(n) sequential terms where F(n) is the n-th Fibonacci number (A000045(n)). Sequence gives the sum of terms in the n-th group. A301809

Number of compositions of n into parts with distinct multiplicities and with exactly nine parts. A321779

Number of partitions of n into colored blocks of equal parts, such that all colors from a set of size ten are used and the colors are introduced in increasing order. A327293