Properties of the Number 1820

One Thousand Eight Hundred Twenty

Basics

Value: 1819 → 1820 → 1821

Parity: even

Prime: No

Previous Prime: 1811

Next Prime: 1823

Digit Sum: 11

Digital Root: 2

Palindrome: No

Factorization: 2 ² × 5 × 7 × 13

Divisors: 1, 2, 4, 5, 7, 10, 13, 14, 20, 26

Polygonal

Triangular: No

Square: No

Pentagonal: Yes

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2730 Try Today's Challenge

Representations

Binary: 11100011100

Octal: 3434

Duodecimal: 1078

Hexadecimal: 71c

Square: 3312400

Square Root: 42.661458015403085

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

Pentagonal numbers: a(n) = n*(3·n-1)/2. A326

Binomial coefficient binomial(n,4) = n*(n-1)*(n-2)*(n-3)/24. A332

a(n) = binomial(4n,n). A5810

Spt function: total number of smallest parts (counted with multiplicity) in all partitions of n. A92269

Triangle read by rows: T(n, k) = binomial(n + k, 2·k). A85478

Triangle of Fibonomial coefficients, read by rows. A10048

a(n) = binomial(n², n). A14062

a(n) = binomial(2ⁿ, n). A14070

Triangle read by rows: T(n, k) = binomial(2n, 2k). A86645

Multiples of 20 containing a 20 in their decimal representation. A121040