Properties of the Number -1809

Eight Hundred Nine

Basics

Value: -1810 → -1809 → -1808

Parity: odd

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ³ × 67

Divisors: 1, 3, 9, 27, 67, 201, 603, 1809

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: -11100010001

Octal: -3421

Duodecimal: -1069

Hexadecimal: -711

Square: 3272481

Square Root: 42.532340636273474

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

Expansion of ∏_m>=1 ((1+q^2·m-1)/(1+q^2·m))³. A29840

Inverse Euler transform applied once to {1,-1,0,0,0,...}, twice to {1,0,0,0,0,...}, or three times to {1,1,1,1,1,...}. A320767

Triangle read by rows: Polynomial coefficients per comment. A290053

Inverse binomial transform of the number of overpartitions (A015128). A294499

G.f. A(x) satisfies: A(x) = x·exp(A(-x) - A(-x²)/2 + A(-x³)/3 - A(-x⁴)/4 + ...). A307366

Signed array used for numerators of generating functions of the column sequences of array A090452. A91029

For all n >= 2, ∑_{2<=k<=n, gcd(k,n)>1} a(k) = 1. a(1)=1. A124385

Multiples of 9 containing a 9 in their decimal representation. A121029

Strictly superdiagonal compositions: compositions (p1, p2, p3, ...) of n such that π > i. A238874

a(n) = n*(5·n - 1)/2. A5476