Properties of the Number 18990

Eighteen Thousand Nine Hundred Ninety

Basics

Value: 18989 → 18990 → 18991

Parity: even

Prime: No

Previous Prime: 18979

Next Prime: 19001

Digit Sum: 27

Digital Root: 9

Palindrome: No

Factorization: 2 × 3 ² × 5 × 211

Divisors: 1, 2, 3, 5, 6, 9, 10, 15, 18, 30

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 100101000101110

Octal: 45056

Duodecimal: ABA6

Hexadecimal: 4a2e

Square: 360620100

Square Root: 137.8042089342702

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

a(n) is the number of partitions of 3n that can be obtained by adding together three (not necessarily distinct) partitions of n. A2220

Number of ways to cover (without overlapping) a ring lattice (necklace) of n sites with molecules that are 9 sites wide. A58364

At stage 1, start with a unit equilateral equiangular triangle. At each successive stage add 3*(n-1) new triangles around outside with edge-to-edge contacts. Sequence gives number of triangles (regardless of size) at n-th stage. A64412

Rounded sums of the non-integer cube roots of n, as partitioned by the integer roots: round(∑_{j=n³+1..(n+1)³-1} j^1/3). A248575

G.f. satisfies: A(x) = 1/(1 + x·A(x⁶)) and also the continued fraction: 1+x·A(x⁷) = [1;1/x,1/x⁶,1/x³⁶,1/x²¹⁶,...,1/x^{6^(n-1}),...]. A101916

Molien series for full 8 X 8 Siegel modular group H₃ of order 371589120. A27633

Expansion of Molien series for 8-dimensional complex Clifford group of genus 3 and order 743178240. A39946

Triangle T(n,k) (n >= 2, 1 <= k <= n) read by rows: number of linearly inducible orderings of n points in k-dimensional Euclidean space. A71223

Structured triakis octahedral numbers (vertex structure 4). A100171

Numbers which do not reach zero under either of the iterations: x -> floor(sqrt(x)) * (x - floor(sqrt(x))²) or y -> ceiling(sqrt(y)) * (ceiling(sqrt(y))² - y). A219963