16685
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
- 8
- Divisor Sum
- 20736
- Proper Divisor Sum (Aliquot Sum)
- 4051
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12880
- Möbius Function
- -1
- Radical
- 16685
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 128
- 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
- The array in A059216 read by antidiagonals in 'up' direction.at n=39A059217
- The array in A059216 read by antidiagonals in the direction in which it was constructed.at n=41A059234
- G.f. satisfies: A(x) = 1/(1 + x*A(x^5)) and also the continued fraction: 1+x*A(x^6) = [1;1/x,1/x^5,1/x^25,1/x^125,...,1/x^(5^(n-1)),...].at n=38A101915
- Numbers n with omega(n) = omega of 3 nearest larger and 3 nearest smaller neighbors.at n=7A101936
- Numbers k such that the sum of the digits of (k^k + k!) is divisible by k.at n=21A109663
- Lengths of bit runs in A123504.at n=45A123505
- Numerators of the convergents of the continued fraction expansion of -zeta(1/2)/sqrt(2*Pi).at n=12A134471
- a(n) = Sum_{k=1..n} k*sigma(k).at n=30A143128
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 0), (0, 0, -1), (1, 0, -1), (1, 1, 1)}.at n=8A149658
- a(1) = 1, and for each k >=2, a(k) is the smallest number n such that n/sin(n) > a(k)/sin(a(k)), so that a(1)/sin(a(1)) > a(2)/sin(a(2)) > ... > a(k)/sin(a(k)) > ...at n=37A172445
- Numbers k such that 4^k + 25 is prime.at n=31A204388
- Numbers k such that Sum_{j=1..k} sigma(j)^j == 0 (mod k).at n=5A229208
- Solution of the complementary equation a(n) = 2*a(n-1) - a(n-2) + b(n-1) -1, where a(0) = 1, a(1) = 2, b(0) = 3, and (a(n)) and (b(n)) are increasing complementary sequences.at n=43A294867
- a(n) = A333552(A333551(n)): indices of terms in Recamán's sequence A005132 where the construction avoided a record-sized collision.at n=40A333553
- a(n) is the smallest integer k > 0 such that 10^(-n-1) < |cos(k) - round(cos(k))| < 10^(-n).at n=5A345670
- Expansion of Sum_{k>0} (x / (1 - 2 * x^k))^k.at n=14A360801