Properties of the Number 20681

Twenty Thousand Six Hundred Eighty-One

Basics

Value: 20680 → 20681 → 20682

Parity: odd

Prime: Yes

Previous Prime: 20663

Next Prime: 20693

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 20681

Divisors: 1, 20681

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000011001001

Octal: 50311

Duodecimal: BB75

Hexadecimal: 50c9

Square: 427703761

Square Root: 143.80890097626084

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

Prime number spiral (clockwise, South spoke). A54566

Primes p such that p-1 and p+1 each contain at least one cubed prime in their prime factorization. A162870

a(n) = (A112565(n) - 1)/n for n>=1. A112566

Non-palindromic balanced primes in base 2. A256081

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

Number of distinct values taken by 7th derivative of x^x^...^x (with n x's and parentheses inserted in all possible ways) at x=1. A215796

Primes congruent to 2 mod 61. A142800

Number of partitions of n such that the (sum of distinct even parts) = floor(n/2). A284610

a(n) = 2·a(n-1) - a(n-2) + a([n/2]), where a(0) = 1, a(1) = 1, a(2) = 1. A298414

Number of 4-element intersecting families (with not necessarily distinct sets) of an n-element set. A52389