Properties of the Number 19987

Nineteen Thousand Nine Hundred Eighty-Seven

Basics

Value: 19986 → 19987 → 19988

Parity: odd

Prime: No

Previous Prime: 19979

Next Prime: 19991

Digit Sum: 34

Digital Root: 7

Palindrome: No

Factorization: 11 × 23 × 79

Divisors: 1, 11, 23, 79, 253, 869, 1817, 19987

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 100111000010011

Octal: 47023

Duodecimal: B697

Hexadecimal: 4e13

Square: 399480169

Square Root: 141.37538682528864

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

Reflected tetranacci numbers A073817. A74058

Triangle read by rows T(n, k) = number of non-equivalent ways to place k non-attacking ferses on an n X n board. A278688

a(n) = prime(n)*T(n), where T = A000217. A196421

Number of partitions of n which can themselves be subdivided into two partitions whose sums differ by 1 at most. A276107

Number of non-equivalent ways to place 5 non-attacking ferses on an n X n board. A278684

Numbers k such that gcd(3k,8^k+1) = 3 but k does not divide the numerator of B(2k) (the Bernoulli numbers). A70193

The number of tilings of a 5 X (3n) floor with 1 X 3 trominoes. A236576

a(n) = a(n-1) - a(n-2) + a(n-3) + a(n-4), a(0)=4, a(1)=1, a(2)=-1, a(3)=1. A73937

Number of set partitions of [n] such that the difference between each element and its block index is a multiple of six. A274839

Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite MFS = ZSM-57 H1.5[Al1.5Si34.5O72] starting with a T2 atom. A19176