Properties of the Number 21687

Twenty-One Thousand Six Hundred Eighty-Seven

Basics

Value: 21686 → 21687 → 21688

Parity: odd

Prime: No

Previous Prime: 21683

Next Prime: 21701

Digit Sum: 24

Digital Root: 6

Palindrome: No

Factorization: 3 × 7229

Divisors: 1, 3, 7229, 21687

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010010110111

Octal: 52267

Duodecimal: 10673

Hexadecimal: 54b7

Square: 470325969

Square Root: 147.2650671408532

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

Number of partitions of n with up to ten distinct kinds of 1. A320697

Indices of primes in sequence defined by A(0) = 67, A(n) = 10·A(n-1) - 23 for n > 0. A101529

Number of -1..1 arrays x(0..n-1) of n elements with zero sum and no two consecutive declines, no adjacent equal elements, and no element more than one greater than the previous (random base sawtooth pattern). A200174

Take a squarefree semiprime and take the difference of its prime factors. If it is a squarefree semiprime repeat the process. Sequence lists the squarefree semiprimes that generate other squarefree semiprimes only in the first k steps of this process. Case k = 4. A296811

Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only in a 00100-11111-00100 pattern in any orientation. A147005

Decimal expansion of 1/683. A21687