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Properties of the Number 21021

Twenty-One Thousand Twenty-One

Basics

Value: 21020 → 21021 → 21022

Parity: odd

Prime: No

Previous Prime: 21019

Next Prime: 21023

Digit Sum: 6

Digital Root: 6

Palindrome: No

Factorization: 3 × 7 2 × 11 × 13

Divisors: 1, 3, 7, 11, 13, 21, 33, 39, 49, 77

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001000011101

Octal: 51035

Duodecimal: 101B9

Hexadecimal: 521d

Square: 441882441

Square Root: 144.98620624045586

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 of T0 integer partitions of n. A319564
7 times hexagonal numbers: a(n) = 7·n*(2·n-1). A195320
Sum of all the parts in the partitions of n into 8 squarefree parts. A326444
Pseudoprimes to base 6, written in base 6. A262103
a(n) = binomial(n+4,4)*(2·n+1). A51880
a(n) = (n+1)*binomial(n+8, 8). A56003
Number triangle T(n,k) = binomial(n,k)*binomial(2n,n-k). A110608
a(n) = n·binomial(2·n, n-1). A110609
Absolute value of coefficient of term [xn-3] in characteristic polynomial of maximum matrix A of size n X n, where n >= 3. Maximum matrix A(i,j) is MAX(i,j), where indices i and j run from 1 to n. A112459
Triangle read by rows: t(n,m) = binomial(2·n,2·m) * binomial(n,m). A155495