Properties of the Number 21056

Twenty-One Thousand Fifty-Six

Basics

Value: 21055 → 21056 → 21057

Parity: even

Prime: No

Previous Prime: 21031

Next Prime: 21059

Digit Sum: 14

Digital Root: 5

Palindrome: No

Factorization: 2 ⁶ × 7 × 47

Divisors: 1, 2, 4, 7, 8, 14, 16, 28, 32, 47

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001001000000

Octal: 51100

Duodecimal: 10228

Hexadecimal: 5240

Square: 443355136

Square Root: 145.10685717773643

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

Partial sums of A001157: ∑_j=1..n sigma₂(j). A64602

Expansion of e.g.f. 4 / (5 - 4·x - exp(4·x)). A355112

Binomial transform of the tribonacci sequence A000073 (shifted left twice). A117189

Expansion of 2 - exp(-1 + sqrt(1-4x)). A101682

Numbers k such that 60·R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k. A56658

Regular triangle read by rows where T(n, k) is the number of set partitions of {1, ..., n} with no block containing k cyclically successive vertices, n >= 1, 2 <= k <= n + 1. A323955

∑_k=1..2n-1 J(4·n,k)*k², where J(i,j) is the Jacobi symbol. A97544

Least positive k such that (10ⁿ+1)ⁿ + k is prime. A121521

Number of (w,x,y) with all terms in {0,...,n} and w ≠ min(|w-x|, |x-y|, |y-w|). A213492

Expansion of ∏_k>=0 ((1+x^4·k+1)/(1-x^4·k+1))². A261650