9009
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 17472
- Proper Divisor Sum (Aliquot Sum)
- 8463
- 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
- 4320
- Möbius Function
- 0
- Radical
- 3003
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 39
- 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
- a(n) = (10n+1)*(10n+9).at n=9A001535
- Number of tree-rooted bridgeless planar maps with two vertices and n faces.at n=8A002740
- Numbers that are the sum of 11 positive 7th powers.at n=44A003378
- Degrees of irreducible representations of alternating group A_13.at n=43A003868
- Degrees of irreducible representations of symmetric group S_13.at n=76A003877
- Degrees of irreducible representations of symmetric group S_13.at n=77A003877
- Denominator of n!!/(n+3)!!.at n=10A004733
- Number of walks on cubic lattice.at n=32A005570
- Centered cube numbers: n^3 + (n+1)^3.at n=16A005898
- Numbers that are palindromic in bases 2 and 10.at n=12A007632
- Let j = | i - i_written_backwards |, k = j + j_written_backwards; then k is in this sequence.at n=39A008920
- Coordination sequence for sigma-CrFe, Position Xd.at n=24A009959
- sec(log(x+1)-sin(x))= 1+3/4!*x^4-30/5!*x^5+180/6!*x^6-1113/7!*x^7...at n=8A013220
- Divisors of 999999.at n=48A027892
- Palindromes of the form k*(k+8).at n=5A028568
- Palindromic lucky numbers.at n=25A031161
- Lucky numbers that are both palindromic and nonprime.at n=20A031880
- a(n) = binomial(n+4,4)*(4*n+5)/5.at n=10A034263
- G.f.: 1/((1-x)*(1-x^2))^3.at n=20A038163
- Palindromes that start with 9.at n=12A043044