Properties of the Number 21919

Twenty-One Thousand Nine Hundred Nineteen

Basics

Value: 21918 → 21919 → 21920

Parity: odd

Prime: No

Previous Prime: 21911

Next Prime: 21929

Digit Sum: 22

Digital Root: 4

Palindrome: No

Factorization: 23 × 953

Divisors: 1, 23, 953, 21919

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010110011111

Octal: 52637

Duodecimal: 10827

Hexadecimal: 559f

Square: 480442561

Square Root: 148.0506670028879

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

T(n,k)=Number of nXk 0..2 arrays with diagonals and rows unimodal and antidiagonals nondecreasing. A224310

T(n,k)=Number of nXk 0..2 arrays with rows unimodal and antidiagonals nondecreasing. A224374

T(n,k)=Number of nXk 0..2 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing. A223933

T(n,k)=Number of nXk 0..2 arrays with rows and columns unimodal and antidiagonals nondecreasing. A224057

Number of days after Jan 01 1000 such that the date written in the format DDMMYYYY is palindromic. A210885

a(n) is such that the a(n)-th composite number is (n-th prime)². A120389

Number of n X 2 0..2 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing. A223927

Number of endofunctions on [n] such that the number of elements that are mapped to i is a multiple or a divisor of i. A364344

Consider all integer triples (i,j,k), j >= k > 0, with binomial(i+2,3)=j³+k³, ordered by increasing i; sequence gives j values. A54206

Expansion of ∏_{i>=1, j>=1} (1 + x^{i*(2·j - 1})). A327731