Properties of the Number 20993

Twenty Thousand Nine Hundred Ninety-Three

Basics

Value: 20992 → 20993 → 20994

Parity: odd

Prime: No

Previous Prime: 20983

Next Prime: 21001

Digit Sum: 23

Digital Root: 5

Palindrome: No

Factorization: 7 × 2999

Divisors: 1, 7, 2999, 20993

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001000000001

Octal: 51001

Duodecimal: 10195

Hexadecimal: 5201

Square: 440706049

Square Root: 144.88961315429066

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

Numbers k such that k²+k+2 is a palindrome. A27712

Least non-balanced x (i.e., not in A020492) such that σ(p(n),x)/φ(x) is an integer, where p(n) = n-th prime. A78540

The number of times a point sum n is attained in all 7⁶ permutations of throwing 7 dice. A166322

Number of ways to arrange 4 nonattacking triangular rooks on an nXnXn triangular grid. A193982

a(n) is the least k such that A261865(k) = A005117(n). A262036

Numbers k such that 69·2^k+1 is prime. A32384

Squarefree semiprimes k such that k+1 is the product of three distinct primes and k+2 is the product of four distinct primes. A376352

a(n) = T(n,0) + T(n,1) + ... + T(n,[ n/2 ]), T given by A026703. A26711

T(n,k) is the number of ways to arrange k nonattacking triangular rooks on an nXnXn triangular grid. A193986

a(n) is the least integer k such that some multiple of sqrt(k) falls strictly between n and n+1. A261865