Properties of the Number 21081

Twenty-One Thousand Eighty-One

Basics

Value: 21080 → 21081 → 21082

Parity: odd

Prime: No

Previous Prime: 21067

Next Prime: 21089

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 7027

Divisors: 1, 3, 7027, 21081

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001001011001

Octal: 51131

Duodecimal: 10249

Hexadecimal: 5259

Square: 444408561

Square Root: 145.19297503667318

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

Number of compositions (ordered partitions) of n into square parts (A000290) such that no two adjacent parts are equal (Carlitz compositions). A301503

Sum of the largest parts of the partitions of n into 9 parts. A326473

Numbers whose square starts with 4 identical digits. A132391

a(n) = 13·n² + 7·n + 1. A168240

For 1<=x<=n, 1<=y<=n, with gcd(x,y)=1, write 1 = gcd(x,y) = u·x+v·y with u,v minimal; a(n) = sum of the values of u²+v². A345431

Odd numbers k such that φ(k) and cototient(k) have the same prime signature. A280927

Numbers whose square starts with exactly 4 identical digits. A346940

Numbers k such that k⁶ - 2 and k⁶ + 2 are both primes. A154938

Number of fusenes with 26 hexagons, C_2v symmetry and containing n carbon atoms. A123662

Numbers k such that (2·10^k - 23)/3 is prime. A293000