Properties of the Number 21855

Twenty-One Thousand Eight Hundred Fifty-Five

Basics

Value: 21854 → 21855 → 21856

Parity: odd

Prime: No

Previous Prime: 21851

Next Prime: 21859

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 3 × 5 × 31 × 47

Divisors: 1, 3, 5, 15, 31, 47, 93, 141, 155, 235

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010101011111

Octal: 52537

Duodecimal: 10793

Hexadecimal: 555f

Square: 477641025

Square Root: 147.83436677579405

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 partitions of n in which the sequence of the sum of the same summands is increasing. A304428

a(n) = (n-1)*(2·n-1)*(3·n-1). A33594

Number of 0..n arrays x(0..4) of 5 elements with each no smaller than the sum of its previous elements modulo (n+1). A200254

a(0) = 1, a(n) = 13·n² + 2 for n>0. A10004

Concatenate Fibonacci(n+2), Fibonacci(n) and Fibonacci(n+4). A134551

Number of (n+1) X (2+1) 0..2 arrays with no element unequal to a strict majority of its horizontal, diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order. A231390

a(0) = a(1) = a(2) = 1; thereafter a(n) = a(n-1) - (-1)ⁿ*a(n-2) + 2·a(n-3). A329301

Products k of 4 distinct primes (or tetraprimes) such that k has no squarefree neighbors. A364141

Least k such that 1+2+...+k >= E{1,2,...,n}, where E is the 4th elementary symmetric function. A27918

Triangle read by rows, T(n,k) = ∑_j=0..n (-1)^n-j*C(-j,-n)*L(j,k), L the unsigned Lah numbers A271703, for n>=0 and 0<=k<=n. A271704