Properties of the Number 21397

Twenty-One Thousand Three Hundred Ninety-Seven

Basics

Value: 21396 → 21397 → 21398

Parity: odd

Prime: Yes

Previous Prime: 21391

Next Prime: 21401

Digit Sum: 22

Digital Root: 4

Palindrome: No

Factorization: 21397

Divisors: 1, 21397

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001110010101

Octal: 51625

Duodecimal: 10471

Hexadecimal: 5395

Square: 457831609

Square Root: 146.27713423498562

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 of the form n² + 81. A256775

Primes p for which the period of reciprocal 1/p is (p-1)/12. A56217

Smaller member of a pair (p,q) of cousin primes such that p and q are in different centuries. A160440

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

Prime time primes on 6-digit clocks, second definition: primes of the form HMMSS where H, MM, SS are primes, H < 24, MM and SS < 60. A295013

Expansion of x/((1 - x - x⁴)*(1 - x)⁵). A145134

Let A = A025584. a(n) is the smallest A(m) such that the interval (A(m)*n, A(m+1)*n) contains no primes from A. A207820

Euclid-Mullin sequence (A000945) with initial value a(1)=19 instead of a(1)=2. A51312

First term of weak prime sextet: p(m+1)-p(m) < p(m+2)-p(m+1) < p(m+3)-p(m+2) < p(m+4)-p(m+3) < p(m+5)-p(m+4). A54828