16865
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 20244
- Proper Divisor Sum (Aliquot Sum)
- 3379
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 13488
- Möbius Function
- 1
- Radical
- 16865
- 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
- 66
- 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 period 59.at n=24A020398
- Expansion of 1/((1-4x)(1-10x)(1-11x)(1-12x)).at n=3A028164
- Numbers k such that k^2 is palindromic in base 4.at n=23A029986
- Gaps of 9 in sequence A038593 (upper terms).at n=14A038658
- a(n) = (n+5)^3 - n^3.at n=31A038867
- Triangle T(n,k) giving the number of simple matroids of rank k on n labeled points (n >= 2, 2 <= k <= n).at n=25A058720
- Number of rank-(n-2) simple matroids on S_n.at n=4A100728
- 3n^3 - 2n^2 + n - 1.at n=17A130885
- G.f.: A(x) = exp( Sum_{n>=1} 5*5^A112765(n) * x^n/n ), where A112765 is the exponent of the highest power of 5 dividing n.at n=17A195760
- a(n) = Sum_{i=0..n} digsum_9(i)^3, where digsum_9(i) = A053830(i).at n=45A231686
- G.f. satisfies: A(x) = (1+x+x^2) * A(x^2)^2.at n=32A237651
- Numbers n such that A242719(n) = (prime(n))^2+1 and A242720(n) - A242719(n) = 2*(prime(n)+1).at n=20A246748
- a(n) = floor(c*s*a(n-1)) + floor(d*r*a(n-2)), where r = (1+sqrt(5))/2, s = r/(r-1), c = 1, d = 1, a(0) = 1, a(1) = 2.at n=9A275857
- E.g..f. A(x) satisfies: 1 = ...(((( A(x) - a(2)*x )^2 - a(3)*x^2 )^3 - a(4)*x^3 )^4 - a(5)*x^4 )^5 -..., with a(0) = a(1) = 1.at n=9A277039
- Triangle read by rows: T(n,k) = number of rooted signed trees with n nodes and k positive edges (0 <= k < n).at n=47A304489
- Triangle read by rows: T(n,k) = number of rooted signed trees with n nodes and k positive edges (0 <= k < n).at n=52A304489
- Numbers k such that both k and k+2 are de Polignac numbers (A006285).at n=24A330284
- Primitive terms of A338890.at n=31A338892