Properties of the Number 21393

Twenty-One Thousand Three Hundred Ninety-Three

Basics

Value: 21392 → 21393 → 21394

Parity: odd

Prime: No

Previous Prime: 21391

Next Prime: 21397

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 2377

Divisors: 1, 3, 9, 2377, 7131, 21393

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001110010001

Octal: 51621

Duodecimal: 10469

Hexadecimal: 5391

Square: 457660449

Square Root: 146.26346091898688

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

Triangle read by rows: T(n,k) = number of reversible string structures of length n using exactly k different symbols. A284949

a(n) = floor(6ⁿ/(3+sqrt(3))ⁿ). A240735

Number of reversible string structures with n beads using exactly five different colors. A56329

Let R(i,j) be the rectangle with antidiagonals 1; 2,3; 4,5,6; ...; the n-th Lucas number is in antidiagonal a(n). A57045

Number of distinct characteristic polynomials for 3 X 3 matrices with entries from {0, 1, ..., n}. A366551

a(n) = [ a(n-1)/a(1) ] + [ a(n-1)/a(2) ] + ... + [ a(n-1)/a(n-1) ] for n >= 3, with initial terms 2,1. A22874

Solution of the complementary equation a(n) = 2·a(n-1) - b(n-2), where a(0) = 3, a(1) = 5, b(0) = 1, b(1) = 2, and (a(n)) and (b(n)) are increasing complementary sequences. A295060

Binomial transform of [1, 2, 3, 4, 0, 0, 0, ...]. A139488

Integers that concatenate 3 counts: the number of terms in the sequence so far, the number of primes in the sequence so far, the number of digits in the sequence so far, with a(1)= 113. The sequence is always extended with the smallest available integer not leading to a contradiction or a dead end. A309617

Decimal expansion of 1/389. A21393