9724
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 21168
- Proper Divisor Sum (Aliquot Sum)
- 11444
- 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
- 3840
- Möbius Function
- 0
- Radical
- 4862
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 166
- 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
- Triangle of Gaussian binomial coefficients [ n,k ] for q = 21.at n=13A022185
- Triangle of Gaussian binomial coefficients [ n,k ] for q = 21.at n=11A022185
- a(n) = (1/(4n-1))*C(4n,2n).at n=5A024491
- Number of bracelets (turnover necklaces) of n beads of 2 colors, 7 of them black.at n=18A032280
- (Terms in A014476)/2.at n=32A051497
- Partial sums of A051740.at n=9A051877
- a(n) = n^3 + n^2 + n + 1.at n=21A053698
- Third diagonal of array in A059347.at n=17A059348
- Numbers of the form (2i)! (2j)! / i! j! (i + j)!.at n=39A068514
- Triangle read by rows in which row n contains (2i)!*(2j)!/(i!*j!*(i+j)!) for i + j = n, i = 0..n.at n=56A068555
- Expansion of (1 + x*C)*C, where C = (1 - (1 - 4*x)^(1/2))/(2*x) is the g.f. for Catalan numbers, A000108.at n=9A068875
- Sums of terms of groups in A075626.at n=25A075629
- Array A(x,y) giving the position of the y-th x in A007001 listed by rising antidiagonals.at n=46A085180
- Number of fixed points in range [A014137(n-1)..A014138(n-1)] of permutation A089864.at n=20A089408
- Short leg of primitive Pythagorean triangles having legs that add up to a square, sorted on hypotenuse.at n=29A089547
- Self-convolution of repeated Catalan numbers.at n=17A104722
- Triangle read by rows: T(n,k) is the number of Grand Dyck paths of semilength n and having k returns to the x-axis.at n=45A108747
- Initial members of abundant quintuplets, i.e., values of k such that (k, k+2, k+4, k+6, k+8) are all abundant numbers.at n=2A108926
- Triangle read by rows: T(n,k) is the number of Grand Dyck paths of semilength n that cross the x-axis k times (n>=1, k>=0).at n=36A118920
- Triangle T(n,k) = lcm(1,...,2*n+2)/((k+1)*binomial(2*k+2,k+1)).at n=40A120101