Properties of the Number 20857

Twenty Thousand Eight Hundred Fifty-Seven

Basics

Value: 20856 → 20857 → 20858

Parity: odd

Prime: Yes

Previous Prime: 20849

Next Prime: 20873

Digit Sum: 22

Digital Root: 4

Palindrome: No

Factorization: 20857

Divisors: 1, 20857

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000101111001

Octal: 50571

Duodecimal: 100A1

Hexadecimal: 5179

Square: 435014449

Square Root: 144.4195277654653

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

Largest prime factor of 2ⁿ + 1. A2587

Primes that divide at least one term of Sylvester's sequence s = A000058: s(n+1) = s(n)² - s(n) + 1, s(0) = 2. A7996

Primes of form n² + 20736. A256840

Largest prime factor of 8ⁿ + 1. A274905

For p = prime(n), a(n) is the smallest prime q such that pq is a base-2 pseudoprime; that is, 2^pq-1 = 1 mod pq; a(n) is 0 if no such prime exists. A85012

Primes that are palindromic in base 11. A29978

Irregular triangle in which row n has all primes q such that prime(n)*q is a base-2 Fermat pseudoprime. A180471

Largest primitive factor of 2²ⁿ⁺¹ + 1. A2589

List of primitive prime divisors of the Jacobsthal numbers A001045 in their order of occurrence. A129738

Diagonal sums of triangle A055249. A79282