Properties of the Number 21491

Twenty-One Thousand Four Hundred Ninety-One

Basics

Value: 21490 → 21491 → 21492

Parity: odd

Prime: Yes

Previous Prime: 21487

Next Prime: 21493

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 21491

Divisors: 1, 21491

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001111110011

Octal: 51763

Duodecimal: 1052B

Hexadecimal: 53f3

Square: 461863081

Square Root: 146.5980900284857

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

Initial term in sequence of four consecutive primes separated by 3 consecutive differences each <=6 (i.e., when d=2,4 or 6) and forming d-pattern=[2,6,4]; short d-string notation of pattern = [264]. A78848

a(n) = (n³)/2 + (3·n²)/2 + 3·n + 3. A127873

Prime numbers of the form (x³)/2+(3x²)/2+3x+3. A127874

Numbers that are the sum of six fourth powers in five or more ways. A345562

Numbers that are the sum of six fourth powers in exactly five ways. A345817

Let (p1,p2), (p3,p4) be pairs of twin primes with p1·p2=p3+p4-1; sequence gives values of p1. A47976

Primes congruent to 15 mod 59. A142742

Primes that remain prime through 2 iterations of function f(x) = 8x + 1. A23260

Smallest prime factor of prime(n)! / prime(n)# + 1. A103891

Smallest member of a pair of consecutive twin prime pairs that have three primes between them. A89635