16668
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 18
- Divisor Sum
- 42224
- Proper Divisor Sum (Aliquot Sum)
- 25556
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5544
- Möbius Function
- 0
- Radical
- 2778
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 3
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
- 115
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Numbers whose base-5 representation contains exactly three 1's and three 3's.at n=21A045247
- Beastly (or hateful) numbers: numbers containing the string 666 in their decimal expansion.at n=33A051003
- Number of unlabeled 3-element intersecting families (with not necessarily distinct sets) of an n-element set.at n=13A055484
- Numbers k such that numerator(Bernoulli(2*k)/(2*k)) is different from numerator(Bernoulli(2*k)/(2*k*(2*k-1))).at n=63A090495
- Recurrence sequence based on positions of digits in decimal places of phi, the Golden Ratio = (1+sqrt(5))/2.at n=11A098324
- Numbers k such that k^2 is the concatenation of two numbers m and 8*m.at n=7A115550
- A functionally symmetric Polynomial as a triangle of coefficients: p(x,n)=If[n == 0, 1, (x + 1)^n + 2^(n - 2)*Sum[(3^(m-1) + 2*m-1 )*x^m*(1 + x^(n - 2*m)), {m, 1, n - 1}]].at n=38A146957
- A functionally symmetric Polynomial as a triangle of coefficients: p(x,n)=If[n == 0, 1, (x + 1)^n + 2^(n - 2)*Sum[(3^(m-1) + 2*m-1 )*x^m*(1 + x^(n - 2*m)), {m, 1, n - 1}]].at n=42A146957
- Coefficient of x in the reduction by x^2->x+1 of the polynomial p(n,x) defined below in Comments.at n=16A192747
- G.f. satisfies A(x) = (1 + x*A(x)^2) * (1 + x^2*A(x)^6).at n=7A200718
- Consider the spiral of Theodorus (A072895). This sequence is closely related to A224269 and gives the number of k successive revolutions such that the triangles are closer to 360 degrees than any previous triangles.at n=24A227626
- Number of partitions p of n containing ceiling((min(p) + max(p))/2) as a part.at n=41A238484
- Number of lines through at least two points of a centered hexagonal grid of size n.at n=9A241220
- Number of partitions of n such that (number parts having multiplicity 1) is not a part and (number of parts > 1) is a part.at n=49A241512
- Numbers k such that k-1 | concat(k, k+1).at n=15A281233
- Expansion of Sum_{p prime, i>=1} x^(p^i)/(1 - x^(p^i)) / Product_{p prime, j>=1} (1 - x^(p^j)).at n=39A281616
- Numbers k such that 2^k + 2*k + 1 is prime.at n=13A301634
- Multiples of 1852.at n=9A303272
- a(n) = 6*(n - 1)*(81*n - 104) for n >= 1.at n=6A304837