9909
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 14720
- Proper Divisor Sum (Aliquot Sum)
- 4811
- 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
- 6588
- Möbius Function
- 0
- Radical
- 1101
- Omega Function (Ω)
- 4
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 135
- 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
- no
- Odd
- yes
Appears in sequences
- Multiplicity of highest weight (or singular) vectors associated with character chi_92 of Monster module.at n=38A034480
- Numbers having three 9's in base 10.at n=18A043527
- Numbers k such that sigma(k^2 + 1) == 0 (mod k).at n=29A067719
- Treated as strings, n begins with Floor(sqrt(n)).at n=32A069086
- Triangle, read by rows, such that the diagonal (A084785) is the self-convolution of the first column (A084784) and the row sums (A084786) gives the differences of the diagonal and the first column.at n=30A084783
- Representative lunar primes.at n=35A088574
- Numbers whose set of base 10 digits is {0,9}.at n=13A097256
- A modular binomial transform of 10^n.at n=8A101678
- A bisection of A101678.at n=4A101679
- Numbers k such that the decimal representation of k is contained as substring in that of the k-th triangular number.at n=10A119238
- Numbers k such that k and k^2 use only the digits 0, 1, 2, 8 and 9.at n=42A136835
- Number of binary strings of length n with equal numbers of 00010 and 01001 substrings.at n=14A164215
- a(1)=10; a(n)=a(n-1)*10 -/+ 1 (alternating).at n=3A179557
- T(n,k)=Number of (n+2)X(k+2) 0..6 arrays with every 3X3 subblock commuting with each horizontal and vertical neighbor 3X3 subblock.at n=7A186572
- T(n,k)=Number of (n+2)X(k+2) 0..6 arrays with every 3X3 subblock commuting with each horizontal and vertical neighbor 3X3 subblock.at n=8A186572
- a(n) = n*(14*n - 11).at n=27A195021
- a(n) = (n-2)*(14*n-39) for n > 2, otherwise a(n) = n.at n=29A195030
- Number of (n+2)X3 binary arrays avoiding patterns 000 and 011 in rows, columns and nw-to-se diagonals.at n=7A202770
- T(n,k) = Number of (n+2) X (k+2) binary arrays avoiding patterns 000 and 011 in rows, columns and nw-to-se diagonals.at n=28A202777
- T(n,k) = Number of (n+2) X (k+2) binary arrays avoiding patterns 000 and 011 in rows, columns and nw-to-se diagonals.at n=35A202777