Properties of the Number 19890

Nineteen Thousand Eight Hundred Ninety

Basics

Value: 19889 → 19890 → 19891

Parity: even

Prime: No

Previous Prime: 19889

Next Prime: 19891

Digit Sum: 27

Digital Root: 9

Palindrome: No

Factorization: 2 × 3 ² × 5 × 13 × 17

Divisors: 1, 2, 3, 5, 6, 9, 10, 13, 15, 17

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 100110110110010

Octal: 46662

Duodecimal: B616

Hexadecimal: 4db2

Square: 395612100

Square Root: 141.0319112825179

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 (n+2)X(k+2) 0..1 arrays with every 3X3 subblock sum of the two maximums of the central row and central column plus the two minimums of the diagonal and antidiagonal nondecreasing horizontally and vertically. A254922

O.g.f.: exp( ∑_n>=1 (σ(2·n²)-σ(n²)) * xⁿ/n ). A195584

Numbers m with m - 1, m + 1 and q(m) - 1 all prime, where q(.) is the strict partition function (A000009). A235346

Numbers n such that for some m, A166133(m)=n, A166133(m+1)=n²-1, in increasing order. A256407

Averages of twin primes such that the sum of the lower, average and upper parts of the twin primes are averages of other twin primes. A132929

Averages of twin prime pairs of the form : sum of two or more consecutive squares. A174716

Numbers n such that for some m, A166133(m)=n, A166133(m+1)=n²-1, in order of increasing m. A256406

Numbers k that are norm-superabundant in Gaussian integers, i.e., A103230(m)/m² < A103230(k)/k² for all m < k. A332321

a(n) = smallest number > a(n-1) such that a(1)*a(2)*...*a(n) + 1 and a(1)*a(2)*...*a(n) - 1 are primes. A51956

a(n) is the least positive number whose divisors have all possible residues mod n. A280171