Properties of the Number 21187

Twenty-One Thousand One Hundred Eighty-Seven

Basics

Value: 21186 → 21187 → 21188

Parity: odd

Prime: Yes

Previous Prime: 21179

Next Prime: 21191

Digit Sum: 19

Digital Root: 1

Palindrome: No

Factorization: 21187

Divisors: 1, 21187

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001011000011

Octal: 51303

Duodecimal: 10317

Hexadecimal: 52c3

Square: 448888969

Square Root: 145.557548756497

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

Numbers that are the sum of seven fourth powers in six or more ways. A345572

Numbers that are the sum of seven fourth powers in exactly six ways. A345828

Primes obtained from other primes by pre-concatenating with 2. A165243

Discriminants of imaginary quadratic fields with class number 19 (negated). A46016

Let F(g,p) be the frequency of g up to prime nextprime(p+1). Primes p such that F(2,p) = F(4,p) and g = 2 or 4. A274122

Primes that remain prime through 3 iterations of function f(x) = 5x + 8. A23286

G.f. satisfies: A(x) = 1/(1 - x·A(x)/(1 - x·A(x)²/(1 - x·A(x)⁴/(1 - x·A(x)⁸/(1 - ...))))), a recursive continued fraction. A192739

Records in A096335 (values). A221181

Primes p such that the concatenations of p and 123456789 in both orders are prime. A384174

a(n) = reverse(2ⁿ) mod 2ⁿ. A103166