Properties of the Number 6640

Six Thousand Six Hundred Forty

Basics

Value: 6639 → 6640 → 6641

Parity: even

Prime: No

Previous Prime: 6637

Next Prime: 6653

Digit Sum: 16

Digital Root: 7

Palindrome: No

Factorization: 2 ⁴ × 5 × 83

Divisors: 1, 2, 4, 5, 8, 10, 16, 20, 40, 80

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1100111110000

Octal: 14760

Duodecimal: 3A14

Hexadecimal: 19f0

Square: 44089600

Square Root: 81.48619514985344

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 n such that n¹⁰²⁴ + 1 is prime (a generalized Fermat prime). A57002

Total number of ON cells at stage 2n of two-dimensional 5-neighbor outer totalistic cellular automaton defined by "Rule 451". A246318

Antidiagonal-sums of the array A377038(n,k) = n-th term of k-th differences of squarefree numbers (A005117). A377039

Numbers k such that φ(x) = k has exactly 9 solutions. A60672

Maximal determinant of an n X n matrix whose elements are a permutation of the first n² prime numbers. A180128

a(n) = n*(n+1)*(11·n+1)/6. A132112

Engel expansion of 1/e = 0.367879... . A59193

Sum of the second largest parts in the partitions of n into 5 parts. A308826

Dirichlet inverse of Fibonacci numbers, when started from A000045(1): 1, 1, 2, 3, 5, 8, 13, 21, ... A349451

Triangle read by rows: T(n,k) = number of collections of up to k+1 disjoint subsets of [n] covering [n], with [0]={}, 0<=k<=n. A381682