6663
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8888
- Proper Divisor Sum (Aliquot Sum)
- 2225
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4440
- Möbius Function
- 1
- Radical
- 6663
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 67
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 54.at n=24A031552
- Positive numbers having the same set of digits in base 4 and base 9.at n=30A037427
- Positive numbers having the same set of digits in base 5 and base 9.at n=41A037432
- Numbers having three 6's in base 10.at n=21A043515
- Numbers whose base-9 representation has exactly 5 runs.at n=10A043634
- Beastly (or hateful) numbers: numbers containing the string 666 in their decimal expansion.at n=9A051003
- Number of ways to partition the sum of all divisors of n (sigma(n), A000203) into distinct positive integers not greater than n.at n=23A079125
- Nearest integer to Sum_{k=0..n} binomial(n,k)/2^(k*(k-1)/2).at n=46A079492
- a(n) = least odd number such that all pairwise sums a(i) + a(j), i < j <= n, are distinct.at n=44A080430
- Numbers n such that sum of divisors of these numbers gives a decimal repdigit.at n=15A096841
- Near-repdigit semiprimes with 6 as repeated digit.at n=15A105987
- Numbers k such that k and k^2 use only the digits 3, 4, 5, 6 and 9.at n=6A137123
- a(n) = 392*n - 1.at n=16A158004
- a(n) = 196*n - 1.at n=33A158225
- a(n) = 34*n^2 - 1.at n=13A158588
- Number of strings of numbers x(i=1..4) in 0..n with sum i*x(i) equal to n*4.at n=30A184704
- a(n) = (a(n-1) + a(n-3))/gcd(a(n-1), a(n-3)) with a(0) =2, a(1) = 3, a(2) = 5.at n=50A214331
- Numbers k such that 2*k!!! - 1 is prime.at n=23A217650
- A boustrophedon triangle.at n=37A227862
- Number of undirected circular permutations i_0, i_1, ..., i_n of 0, 1, ..., n such that i_0+i_1, i_1+i_2, ...,i_{n-1}+i_n, i_n+i_0 are among those k with 6*k-1 and 6*k+1 twin primes.at n=13A228917