Properties of the Number 21557

Twenty-One Thousand Five Hundred Fifty-Seven

Basics

Value: 21556 → 21557 → 21558

Parity: odd

Prime: Yes

Previous Prime: 21529

Next Prime: 21559

Digit Sum: 20

Digital Root: 2

Palindrome: No

Factorization: 21557

Divisors: 1, 21557

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010000110101

Octal: 52065

Duodecimal: 10585

Hexadecimal: 5435

Square: 464704249

Square Root: 146.82302271782856

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 pattern = [2, 4, 6]; short notation = [246] d-pattern. A78847

Least prime p such that x²+x+p produces primes for x=0..n-1 and composite for x=n. A164926

Primes p such that the polynomial x² + x + p generates only primes for x = 0, ..., 4. A187057

Primes p such that the polynomial x² + x + p generates only primes for x = 1..7. A187060

Primes p such that the polynomial x² + x + p generates only primes for x = 1..6. A144051

Initial primes of 5 consecutive primes with consecutive gaps 2, 4, 6, 8. A190814

Initial primes of 6 consecutive primes with consecutive gaps 2,4,6,8,10. A190817

Primes p such that the polynomial x² + x + p generates only primes for x = 1..5. A187058

Primes p such that (p, p+2, p+6, p+12) is a prime quadruple. A172454

Primes q (except greater of twin primes) with result 2 under iterations of {r mod (max prime p < r)} starting at r = q. A175080