9891
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
- 4
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 16432
- Proper Divisor Sum (Aliquot Sum)
- 6541
- 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
- 5616
- Möbius Function
- 0
- Radical
- 3297
- Omega Function (Ω)
- 4
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 122
- 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
- Partial sums of A014138.at n=8A014143
- Numerator of sum of -3rd powers of divisors of n.at n=25A017669
- Expansion of 1/((1-x)*(1-3*x)*(1-4*x)*(1-7*x)).at n=4A021364
- McKay-Thompson series of class 29A for Monster.at n=32A058611
- Diagonal in array of n-gonal numbers A081422.at n=20A081438
- Numbers k such that numerator(Bernoulli(2*k)/(2*k)) is different from numerator(Bernoulli(2*k)/(2*k*(2*k-1))).at n=37A090495
- A convolution triangle of numbers obtained from A034789.at n=33A092083
- Triangle read by rows: T(n,k) is the number of Dyck n-paths with k large components, 0 <= k <= n/2.at n=31A097877
- Triangle read by rows: T(n,k) is the number of k-matchings of the corona K'(n) of the complete graph K(n) and the complete graph K(1); in other words, K'(n) is the graph constructed from K(n) by adding for each vertex v a new vertex v' and the edge vv'.at n=49A100862
- Triangle read by rows: T(n,k) is the number of k-matchings of the corona K'(n) of the complete graph K(n) and the complete graph K(1); in other words, K'(n) is the graph constructed from K(n) by adding for each vertex v a new vertex v' and the edge vv'.at n=50A100862
- Matrix inverse of triangle A099602, read by rows, where row n of A099602 equals the inverse binomial transform of column n of the triangle of trinomial coefficients (A027907).at n=57A104495
- Nonnegative values x of solutions (x, y) to the Diophantine equation x^2+(x+449)^2 = y^2.at n=7A130004
- McKay-Thompson series of class 29A for the Monster group with a(0) = 2.at n=32A136570
- Numbers k such that k and k^2 use only the digits 1, 3, 7, 8 and 9.at n=4A137043
- Triangle T(n,k) = number of forests of labeled rooted trees of height at most 1, with n labels, k of which are used for root nodes and any root may contain >= 1 labels, n >= 0, 0<=k<=n.at n=33A143396
- 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, 1), (-1, 1, -1), (0, 1, 1), (1, -1, -1)}.at n=10A148221
- a(n) = 5*n^2 + 5*n - 9.at n=43A166150
- a(n) is the Severi degree for curves of degree n and cogenus 2.at n=7A171108
- Riordan array ((1/(1-x))^m, x*A000108(x)), m = 2.at n=57A185943
- Triangle T(n,k) = coefficient of x^n in expansion of ((1-sqrt(1-4*x))/((1-x)*2))^k = sum(n>=k, T(n,k) * x^n).at n=46A200965