11985
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 20736
- Proper Divisor Sum (Aliquot Sum)
- 8751
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5888
- Möbius Function
- 1
- Radical
- 11985
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- 81
- 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
- sin(cos(x)*arcsin(x))=x-3/3!*x^3+25/5!*x^5-371/7!*x^7+11985/9!*x^9...at n=4A012481
- exp(cosh(x)*arcsinh(x))=1+x+1/2!*x^2+3/3!*x^3+9/4!*x^4+25/5!*x^5...at n=9A012771
- Numbers whose sum of divisors is a fourth power.at n=28A019422
- a(n) = Sum_{k=floor((n+1)/2)..n} T(k,n-k); i.e., a(n) is the n-th diagonal sum of left-justified array T given by A026998.at n=22A027010
- Integer part of (Product(n^((1 + log(1 + i))/i^2), {i, 1, n})).at n=19A062486
- Nearest integer to (Product(n^((1 + log(1 + i))/i^2), {i, 1, n})).at n=19A062487
- Odd n such that 2*phi(n) < n, but there does not exist an even k < n with phi(k) = phi(n).at n=1A118700
- Primitive elements of A119432.at n=24A119433
- a(n) = (3*n+1)*(5*n+1).at n=28A144459
- Triangle T(n,k) = (-1)^(k+n)*A054655(n,n-k), 0<=k<n, read by rows.at n=24A177938
- G.f.: exp( Sum_{n>=1} A000204(n)^5 * x^n/n ) where A000204 is the Lucas numbers.at n=4A203805
- a(n) = 4*n^3 + 5*n^2 + 2*n + 1.at n=14A204674
- One half of the radical (squarefree kernel) of the abc-triples (a=1, b(n) = A216323(n), c(n) = 1 + b(n)).at n=40A216324
- Number of ways to partition the (vertex) set {1,2,...,n} into any number of classes and then select some unordered pairs (edges) <a,b> such that a and b are in distinct classes of the partition.at n=5A240936
- Magic sums of 4 X 4 magic squares composed of squares.at n=16A271580
- Partial sums of A301692.at n=84A301693
- Expansion of e.g.f. (1 + LambertW(-x))/(1 + 2*LambertW(-x)).at n=5A308863
- Numbers of squares formed by this procedure on n-th step: Step 1, draw a unit square. Step n, draw a unit square with center in every intersection of lines of the figure in step n-1.at n=16A336288