16885
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 28
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 22176
- Proper Divisor Sum (Aliquot Sum)
- 5291
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12240
- Möbius Function
- -1
- Radical
- 16885
- Omega Function (Ω)
- 3
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 172
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Number of n-node labeled acyclic digraphs with 1 out-point.at n=4A003025
- Coordination sequence for MgNi2, Position Mg2.at n=32A009935
- Dirichlet convolution of Fibonacci numbers with Catalan numbers.at n=10A034749
- Areas of a sequence of right-angled figures described below.at n=19A058195
- Triangle read by rows: T(n,k) = number of labeled acyclic digraphs with n nodes, containing exactly n+1-k points of in-degree zero (n >= 1, 1<=k<=n).at n=14A058876
- Numbers n for which there are exactly eight k such that n = k + reverse(k).at n=30A072432
- Prime(a(n)) + ... + prime(a(n)+3) is a square = A051395(n)^2.at n=20A072849
- 75-gonal numbers: a(n) = n*(73*n-71)/2.at n=22A098230
- a(0)=1, a(1)=1, a(n)=7*a(n/2) for n=2,4,6,..., a(n)=6*a((n-1)/2)+a((n+1)/2) for n=3,5,7,....at n=35A116522
- a(n) = ceiling(n^3/3).at n=37A131477
- Partial sums of minimal set of prime-strings in base 10 (A071062).at n=15A172982
- Number of (w,x,y,z) with all terms in {1,...,n} and 3*w = x+y+z.at n=37A212069
- Principal diagonal of the convolution array A213841.at n=14A213842
- Number of n X 6 0..1 arrays with rows and antidiagonals unimodal and columns nondecreasing.at n=6A224144
- Number of 7Xn 0..1 arrays with rows and antidiagonals unimodal and columns nondecreasing.at n=5A224151
- Values of n such that L(14) and N(14) are both prime, where L(k) = (n^2+n+1)*2^(2*k) + (2*n+1)*2^k + 1, N(k) = (n^2+n+1)*2^k + n.at n=41A227517
- Convolution of A006068 (inverse of Gray code) with itself: a(n) = Sum_{k=1..n+1} A006068(k) * A006068(1+n-k).at n=41A268721
- Numbers k such that (73*10^k + 143)/9 is prime.at n=22A272193
- a(n) = n*a(n-1) + n^(1+n mod 2), a(0) = 1.at n=7A344317
- Triangular array read by rows. T(n,k) is the number of labeled directed acyclic graphs on [n] with exactly k nodes of indegree 0.at n=16A361718