Properties of the Number -2021

Twenty-One

Basics

Value: -2022 → -2021 → -2020

Parity: odd

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 5

Digital Root: 5

Palindrome: No

Factorization: 43 × 47

Divisors: 1, 43, 47, 2021

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: -11111100101

Octal: -3745

Duodecimal: -1205

Hexadecimal: -7e5

Square: 4084441

Square Root: 44.955533585978046

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

Alternating row sums of Sheffer triangle A143496 (4-restricted Stirling2 numbers). A193684

Coefficients in the power series expansion of A(x) = ∑_n=-oo..+oo n*(n+1)*(n+2)/6·x^3·n * (1 - xⁿ)^n-2. A357156

First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 342", based on the 5-celled von Neumann neighborhood. A269512

Products of 2 successive primes. A6094

a(n) = n² - 4. A28347

Numerator of 1/4 - 1/n². A61037

Coordination sequence for 3D uniform tiling formed by stacking parallel layers of the 4.6.12 2D tiling (cf. A072154). A299258

Partial sums of A008137. A299276

Numbers whose sum of digits is 5. A52219

a(n) = n concatenated with n + 1. A1704