9911
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 11664
- Proper Divisor Sum (Aliquot Sum)
- 1753
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8320
- Möbius Function
- -1
- Radical
- 9911
- 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
- 73
- 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 solutions to k_1 + 2*k_2 + ... + n*k_n = 0, where k_i are from {-1,0,1}, i=1..n.at n=12A007576
- a(n) = floor( n*(n-1)*(n-2)/29 ).at n=67A011911
- Pseudoprimes to base 52.at n=32A020180
- Largest coefficient in expansion of Product_{i=1..n} (1 + q^i + q^(2i)).at n=11A039826
- a(n) = a(n-1) + a(m) for n >= 4, where m = 2*n - 3 - 2^(p+1) and p is the unique value such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = 1 and a(3) = 3.at n=44A050032
- a(n) = a(n-1) + a(m) for n >= 3, where m = 2*n - 3 - 2^(p+1) and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1 and a(2) = 2.at n=44A050048
- a(n) = a(n-1) + a(m) for n >= 4, where m = 2*n - 3 - 2^(p+1) and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1 and a(2) = a(3) = 3.at n=44A050064
- Numbers n such that 241*2^n-1 is prime.at n=11A050879
- Geometric mean of the digits = 3. In other words, the product of the digits is = 3^k where k is the number of digits.at n=29A061427
- Numbers k such that the product of the digits of k is equal to the sum of the prime factors of k, counted with multiplicity.at n=26A065774
- Numbers n such that the sum of the prime factors of n equals the product of the digits of n.at n=22A067173
- Treated as strings, n begins with Floor(sqrt(n)).at n=34A069086
- a(n) = 9*n^3 - 18*n^2 + 10*n.at n=11A086605
- Duplicate of A007576.at n=12A086821
- Structured rhombic triacontahedral numbers (vertex structure 11).at n=10A100164
- Berend Jan van der Zwaag's conjectured complete list of numbers that start different "expanding periodic loops" under the mapping described in A053392 and A060630.at n=2A103117
- Numbers k such that 10^k - k is prime.at n=4A110065
- Multiples of 11 containing an 11 in their decimal representation.at n=27A121031
- Number of base 27 circular n-digit numbers with adjacent digits differing by 1 or less.at n=7A124726
- Numbers k such that k and k^2 use only the digits 1, 2, 7, 8 and 9.at n=12A137018