9945
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
- 2
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 19656
- Proper Divisor Sum (Aliquot Sum)
- 9711
- 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
- 4608
- Möbius Function
- 0
- Radical
- 3315
- 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
- yes
- Harshad Number
- no
- 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
- no
- Odd
- yes
Appears in sequences
- Quadruple factorial numbers n!!!!: a(n) = n*a(n-4).at n=17A007662
- Quartic (or 4-fold) factorial numbers: a(n) = Product_{k = 0..n-1} (4*k + 1).at n=5A007696
- Number of polynomial symmetric functions of matrix of order n under separate row and column permutations.at n=9A007716
- a(n) = (n+1)*(2*n+1)*(3*n+1)*(4*n+1).at n=4A011245
- Numbers k such that sigma(k) = sigma(k+7).at n=16A015867
- a(n) = (2*n+1)*(10*n+1).at n=22A033574
- Duplicate of A049029.at n=10A048897
- Triangle read by rows, the Bell transform of the quartic factorial numbers A007696(n+1) without column 0.at n=10A049029
- a(n) is the least common multiple of {1, 5, 9, 13, 17, ..., 4n+1} (A016813).at n=4A051539
- Values of m, the main key or generating number for Pythagorean triangles in which S (the odd short leg) and U (the hypotenuse) are twin primes.at n=34A051891
- Number of primitive (aperiodic) reversible strings with n beads using a maximum of three different colors.at n=8A056314
- Number of functions f: {1,2,...,n} -> {1,2,...,n} with even cycles only.at n=6A060435
- Non-palindromic number and its reversal are both multiples of 13.at n=35A062912
- Numbers k that, when expressed in base 4 and then interpreted in base 8, give a multiple of k.at n=45A062923
- Eighth convolution of A000129(n+1) (generalized (2,1)-Fibonacci, called Pell numbers), n>=0, with itself.at n=4A073385
- Product of terms in n-th row of A076110.at n=4A076111
- Expansion of 1/Product_{ n >= 2, n not of the form 2^k-1 } (1 - x^n).at n=53A078657
- 4th-order non-linear ("factorial") recursion: a(0)=a(1)=a(2)=a(3)=1, a(n) = (n+1)*a(n-4).at n=16A081407
- Least positive integer coefficients of power series A(x) such that the coefficients of A(x)^2 + A(x) - 1 consist entirely of squares.at n=73A083352
- a(n) is the largest number such that all of a(n)'s length-n substrings are distinct and divisible by 85.at n=3A093285