9040
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
- 20
- Divisor Sum
- 21204
- Proper Divisor Sum (Aliquot Sum)
- 12164
- 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
- 3584
- Möbius Function
- 0
- Radical
- 1130
- Omega Function (Ω)
- 6
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 21
- 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
- Coordination sequence for FeS2-Pyrite, S position.at n=44A009956
- Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 21 (most significant digit on right).at n=15A029514
- McKay-Thompson series of class 15A for Monster.at n=15A058508
- Numbers k such that 2*7^k - 3 is prime.at n=6A059077
- Numbers k such that phi(x) = k has exactly 11 solutions.at n=31A060674
- Slowest increasing sequence where the absolute difference between the last digit of a(n) and the first digit of a(n+1) equals 9.at n=16A101243
- Real part of absolute Gaussian perfect numbers, in order of increasing magnitude.at n=40A102531
- Norm of the sum of divisors function sigma(n) generalized for Gaussian integers.at n=39A103230
- Expansion of g.f.: 1/( (1+2*x)*(1-2*x-4*x^2)*(1-2*x^2)^2 ).at n=8A121961
- McKay-Thompson series of class 15A for the Monster group with a(0) = 1.at n=15A134783
- Central moment sequence of tr(A^4) in USp(4).at n=9A138354
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 0), (0, 0, 1), (0, 1, -1), (1, -1, -1)}.at n=11A148018
- McKay-Thompson series of class 15A for the Monster group with a(0) = 4.at n=15A153765
- A triangular sequence based on the first level sum of polynomial coefficients: p(x,n,m)=(1 - x)^(n + m + 1)*Sum[k^(n - 1)*(1 - k)^(m - 1)*x^k, {k, 0, Infinity}]/4.at n=14A168217
- Number of nX5 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=3A207805
- T(n,k)=Number of nXk 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=31A207808
- Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=4A207809
- a(1) = 17, a(2) = 80, a(n) = 4*(a(n-1) + a(n-2)) for n >= 3.at n=4A228602
- Let x(0)x(1)x(2)... x(q) denote the decimal expansion of n. Sequence lists the numbers n such that the suffix of decimal expansion x(1)x(2)... x(q) is the x(0)-th divisor of n.at n=27A234314
- Let m_n denote the number which is obtained from n-base representation of m if its digits are written in nondecreasing order; then a(n) is the smallest period of the sequence which is defined by the recurrence b(0)=0, b(1)=1, b(k)=(b(k-1) + b(k-2))_n, for k>=2, or a(n)=0, if there is no such period.at n=40A237671