4009
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 4240
- Proper Divisor Sum (Aliquot Sum)
- 231
- 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
- 3780
- Möbius Function
- 1
- Radical
- 4009
- Omega Function (Ω)
- 2
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 157
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- a(n) = floor( n*(n-1)*(n-2)*(n-3)/29 ).at n=20A011939
- Generalized Catalan Numbers x^3*A(x)^2 + (x-1)*A(x) + 1 =0.at n=14A023431
- Numbers with exactly 7 1's in their ternary expansion.at n=14A023698
- a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-3)*a(3) for n >= 4, with initial terms 1, 0, 1, 1.at n=16A025246
- Numerical distance between m-th and (m+n)-th spheres in loxodromic sequence of spheres in which each 5 consecutive spheres are in mutual contact.at n=16A027674
- Numbers having three 4's in base 9.at n=28A043471
- Numbers k such that the string 0,9 occurs in the base 10 representation of k but not of k-1.at n=42A044341
- Numbers whose base-3 representation contains no 0's and exactly one 2.at n=34A044990
- a(n)=T(n,n+1), array T as in A049723.at n=35A049729
- Expansion of g.f. (1+x-x^2)/((1-x)*(1-3*x)).at n=7A052909
- Expansion of (1+x^2)*(1+x^5)/( Product_{j=1..7} (1-x^j) ).at n=29A060962
- Sum of antidiagonals of A060736.at n=19A061349
- a(n) = (2*n - 1)*(7*n^2 - 7*n + 3)/3.at n=9A063494
- Engel expansion of Gamma(1/4)=3.62560990822190831193...at n=6A068479
- Third differences of partition numbers A000041.at n=62A072380
- Numbers k such that h(k) = h(k-1) + h(k-2), where h(k) = A006577(k) + 1 is the length of the sequence {k, f(k), f(f(k)), ...., 1} in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=20A078418
- Engel expansion of the twin primes constant ~ .660161815846869573927812110014555778432623360284733413319448.at n=5A096189
- Number of partitions of n into parts having at most two prime-factors.at n=29A101049
- a(n) = concatenation of n times each digit of n divided by n.at n=48A111705
- Triangle read by rows: T(n,k) is the number of 0-1-2 trees (i.e., ordered trees with all vertices of outdegree at most two) with n edges and k pairs of adjacent vertices of outdegree 2.at n=38A126218