9900
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 54
- Divisor Sum
- 33852
- Proper Divisor Sum (Aliquot Sum)
- 23952
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 2400
- Möbius Function
- 0
- Radical
- 330
- Omega Function (Ω)
- 7
- 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
- yes
Recreational
- Happy Number
- no
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 73
- 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
- a(n) = ceiling(n*phi^13), where phi is the golden ratio, A001622.at n=19A004968
- Theta series of A_5 lattice.at n=44A008445
- a(n) = (-1 + prime(n+1)^2)/4.at n=44A024701
- a(n) = 2*(n+1)*binomial(n+3,4).at n=8A027789
- a(n) = 15*(n+1)*binomial(n+3,10).at n=2A027795
- Expansion of 1/((1-3x)(1-4x)(1-11x)(1-12x)).at n=3A028052
- a(n) = floor( n(n+1)(n+2)(n+3)(n+4) / (n+(n+1)+(n+2)+(n+3)+(n+4)) ).at n=13A032768
- a(n) = 11*n^2.at n=30A033584
- Number of 2n-bead balanced binary strings of fundamental period 2n, rotationally equivalent to reversed complement.at n=10A045664
- Hexagonal matchstick numbers: a(n) = 3*n*(3*n+1).at n=33A045945
- a(n) = n*(n-1)^2*(n-2).at n=9A047928
- Numbers n such that 227*2^n-1 is prime.at n=18A050865
- Take n-th palindromic prime p, let P = all primes having same digits; a(n) = q-p where q is smallest prime in P >p if q exists; otherwise a(n) = p-r where r is largest prime in P <p if r exists; otherwise a(n) = 0.at n=52A052507
- Numbers k that can be expressed as k = w+x = y*z with w*x = (y+z)^3 where w, x, y, and z are all positive integers.at n=14A057370
- Numbers n such that x^n + x^11 + 1 is irreducible over GF(2).at n=30A057481
- Freestyle perfect numbers n = Product_{i=1,..,k} f_i^e_i where 1 < f_1 < ... < f_k, e_i > 0, such that 2n = Product_{i=1,..,k} (f_i^(e_i+1)-1)/(f_i-1).at n=39A058007
- Triangle read by rows: T(n,k) is the number of labeled commutative semigroups of order n with k idempotents.at n=12A058167
- Numbers k such that phi(x) = k has exactly 11 solutions.at n=35A060674
- Number of irreducible representations of the symmetric group S_n such that their degree is divisible by 3.at n=32A061569
- Half totient of 2^n+1.at n=14A063474