Properties of the Number 20021

Twenty Thousand Twenty-One

Basics

Value: 20020 → 20021 → 20022

Parity: odd

Prime: Yes

Previous Prime: 20011

Next Prime: 20023

Digit Sum: 5

Digital Root: 5

Palindrome: No

Factorization: 20021

Divisors: 1, 20021

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 100111000110101

Octal: 47065

Duodecimal: B705

Hexadecimal: 4e35

Square: 400840441

Square Root: 141.4955829699288

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 having only {0, 1, 2} as digits. A36953

Primes whose sum of digits is 5. A62341

Primes with arithmetic mean of digits = 1 (sum of digits = number of digits). A69710

Primes p whose period of reciprocal equals (p-1)/13. A98680

Primes of the form ((p+1)/2)²+((p-1)/2), where p is prime. A163419

Array of a(n)=a(n-1)*k-((k-1)/(kⁿ)) where a(0)=1 and k=(sqrt(x²-1)+x)² for integers x>=1. A188646

Primes with maximal digit = 2. A106100

Define C(n) by the recursion C(0) = 2·i where i² = -1, C(n+1) = 1/(1 + C(n)), then a(n) = 2*(-1)ⁿ/Im(C(n)) where Im(z) denotes the imaginary part of the complex number z. A69959

a(n) = n² written in base 3. A1738

Smallest n-digit prime with all even digits except the least significant digit. A68691