Properties of the Number 21020

Twenty-One Thousand Twenty

Basics

Value: 21019 → 21020 → 21021

Parity: even

Prime: No

Previous Prime: 21019

Next Prime: 21023

Digit Sum: 5

Digital Root: 5

Palindrome: No

Factorization: 2 ² × 5 × 1051

Divisors: 1, 2, 4, 5, 10, 20, 1051, 2102, 4204, 5255

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001000011100

Octal: 51034

Duodecimal: 101B8

Hexadecimal: 521c

Square: 441840400

Square Root: 144.98275759551547

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

Number T(n,k) of rooted identity trees with n nodes and colored non-root nodes using exactly k colors; triangle T(n,k), n>=1, 0<=k<=n-1, read by rows. A256068

Numbers n such that there are precisely 15 groups of orders n and n + 1. A295995

Each permutation in the list A060117 converted to Site Swap notation, with digits reversed. "Zero throws" (fixed elements) indicated with 0's. A60496

Number of length n self-avoiding walks on the kisrhombille tiling starting at a degree 4 vertex. A326745

a(n) = 1000·n + 20. A157510

Numbers k such that k-1, k-3, k-7 and k-9 are all prime. A64974

a(n) = 25·n² - 5. A158446

Numbers encoded in an alternate, sometimes more compact, binary system with a third, dual-purpose, prefix/delimiter symbol not always required. A140116

Union of all unique coefficients of all powers of the g.f. A(x) of this sequence, starting with A(0)=2 and A'(0)=3. A262975

Number of length n arrays of permutations of 0..n-1 with each element moved by -4 to 4 places and exactly one more element moved upwards than downwards. A263760