Properties of the Number 6721

Six Thousand Seven Hundred Twenty-One

Basics

Value: 6720 → 6721 → 6722

Parity: odd

Prime: No

Previous Prime: 6719

Next Prime: 6733

Digit Sum: 16

Digital Root: 7

Palindrome: No

Factorization: 11 × 13 × 47

Divisors: 1, 11, 13, 47, 143, 517, 611, 6721

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1101001000001

Octal: 15101

Duodecimal: 3A81

Hexadecimal: 1a41

Square: 45171841

Square Root: 81.9817052762383

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 for which 10k+1, 10k+3, 10k+7 and 10k+9 are primes. A7811

Bruckman-Lucas pseudoprimes: k | (L_k - 1), where k is composite and L_k = Lucas numbers A000032. A5845

Odd Fibonacci pseudoprimes: odd composite numbers k such that either (1) k divides Fibonacci(k-1) if k == +-1 (mod 5) or (2) k divides Fibonacci(k+1) if k == +-2 (mod 5). A81264

Number A(n,k) of k-partite partitions of {n}^k into k-tuples; square array A(n,k), n>=0, k>=0, read by antidiagonals. A219727

Number of partitions of n such that smaller parts do not occur more frequently than greater parts. A171979

Numbers m > 1 such that a record number of numbers k have m as the sum of the proper divisors of k. A238895

Concentric 16-gonal numbers. A195146

Third row of number array A082105. A82109

Composite numbers k such that k divides F(k-1) where F(j) are the Fibonacci numbers. A69106

Odd composite integers m such that F(m)² == 1 (mod m), where F(m) is the m-th Fibonacci number. A337231