11850
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 29760
- Proper Divisor Sum (Aliquot Sum)
- 17910
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3120
- Möbius Function
- 0
- Radical
- 2370
- Omega Function (Ω)
- 5
- 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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 37
- 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
- Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= n/2.at n=19A047163
- Number of nonempty subsets of {1,2,...,n} in which exactly 3/4 of the elements are <= n/2.at n=19A047164
- Numbers k such that prime(k+3)-(k+3)*tau(k+3) = prime(k-3)-(k-3)*tau(k-3) where tau(k) = A000005(k) is the number of divisors of k.at n=29A067355
- a(1) = 1; a(n) = Sum_{k=1..n-1} a(floor((n-1)/k)).at n=46A078346
- Pierce expansion of log(2).at n=13A091846
- Triangle read by rows: T(n,k) = number of peakless Motzkin paths of length n and having k ascents (0<=k<=floor(n/3)).at n=55A114712
- Fixed points of permutation A114650.at n=9A114726
- Riordan array ((1-3x+x^2)/(1-4x+3x^2), x(1-2x)/(1-4x+3x^2)).at n=47A147747
- a(n) = n*(6*n^2 + 15*n + 5)/2.at n=15A163833
- Numbers n with property that 42*n+37 is in A175284.at n=12A175285
- a(1)=4. a(n) = a(n-1) + n, if a(n-1)+n is composite. Otherwise a(n) = a(n-1)*n.at n=13A175459
- Number of nX4 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,0,1,1,1 for x=0,1,2,3,4.at n=5A197276
- Number of n X 6 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,0,1,1,1 for x=0,1,2,3,4.at n=3A197278
- T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,0,1,1,1 for x=0,1,2,3,4.at n=39A197280
- T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,0,1,1,1 for x=0,1,2,3,4.at n=41A197280
- Number of ordered triples (w,x,y) with all terms in {1,...,n} and 2*w^2 < x^2 + y^2.at n=27A211800
- Largest number k such that phi(k) = A007374(n).at n=44A224532
- Triangle read by rows: T(n,m) = one-half of number of embeddings of the n-wheel with k = n+1-2m regions (n >= 1, 0 <= m <= floor(n/2)).at n=30A301731
- a(n) = coefficient of x^n*y^n in Product_{n>=1} (1 - (x^n + y^n))^3.at n=26A322214
- Place two n-gons with radii 1 and 2 concentrically, forming an annular area between them. Connect all the vertices with line segments that lie entirely within that area. Then a(n) is the number of regions in that figure.at n=22A337700