Properties of the Number 21357

Twenty-One Thousand Three Hundred Fifty-Seven

Basics

Value: 21356 → 21357 → 21358

Parity: odd

Prime: No

Previous Prime: 21347

Next Prime: 21377

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ³ × 7 × 113

Divisors: 1, 3, 7, 9, 21, 27, 63, 113, 189, 339

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2730 Try Today's Challenge

Representations

Binary: 101001101101101

Octal: 51555

Duodecimal: 10439

Hexadecimal: 536d

Square: 456121449

Square Root: 146.14034350582318

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

Numbers n such that n⁶ + 272 is prime. A161998

a(n) = A104908(n) - 10·A104863(n). A104909

a(n) = ∑_{k=0..floor(n/4)} 2^k * 3^n-3·k * binomial(n-2·k,k) * binomial(n-3·k,k). A390830

Number·such that usigma(x) = (-1)σ(x), where usigma(x) is the sum of unitary divisors of x (A034448) and (-1)σ(x) is defined in A049060 . A258101

From a nim-like game. A3413

a(n) = (2·n³ + 5·n² - 11·n)/2. A162257

Sum of the lengths of the arithmetic progressions in {1,2,3,...,n}, including trivial arithmetic progressions of lengths 1 and 2. A264100

Expansion of e.g.f. (1/x) * Series_Reversion( x / (1 + 3·x*exp(x))^1/3 ). A380081

Numbers having four 5's in base 8. A43444

Least positive integer m such that m¹²*n = x⁴ + y³ + z² for some nonnegative integers x,y,z. A350714