Properties of the Number 21871

Twenty-One Thousand Eight Hundred Seventy-One

Basics

Value: 21870 → 21871 → 21872

Parity: odd

Prime: Yes

Previous Prime: 21863

Next Prime: 21881

Digit Sum: 19

Digital Root: 1

Palindrome: No

Factorization: 21871

Divisors: 1, 21871

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010101101111

Octal: 52557

Duodecimal: 107A7

Hexadecimal: 556f

Square: 478340641

Square Root: 147.88847149118826

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

Primes whose base-3 representation also is the base-2 representation of a prime. A235265

G.f.: x*(1 - x + x²)/((1-x)² * (1 - x - x²)). A104161

Primes p such that p-1 and p+1 are both divisible by fourth powers. A86709

a(n) = 30·n² + 1. A158558

Smallest of 3 consecutive prime numbers such that p1·p2·p3·d1·d2=average of twin prime pairs; p1,p2,p3 consecutive prime numbers; d1(δ)=p2-p1, d2(δ)=p3-p2. A153409

A set of nine consecutive primes forming a 3 X 3 semimagic square with the smallest magic constant (65573). A265614

Primes p such that the greatest prime divisor of p-1 is 5. A61599

Primes of the form 10·3^k + 1. A68715

Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 100 ones. A31868

a(n) = 729·n + 1. A158397