7128
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 40
- Divisor Sum
- 21780
- Proper Divisor Sum (Aliquot Sum)
- 14652
- 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
- 2160
- Möbius Function
- 0
- Radical
- 66
- Omega Function (Ω)
- 8
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 49
- 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
- Number of bipartite partitions of n white objects and 6 black ones.at n=10A002755
- Number of bipartite partitions of n white objects and 10 black ones.at n=6A002759
- Smallest k such that phi(x) = k has exactly n solutions, n>=2.at n=33A007374
- Smallest k such that phi(x) = k has exactly n solutions, n>=0 with Carmichael conjecture.at n=35A014573
- Let I_c(n,d) be maximal number of independent sets in d-regular simple connected graphs with n vertices; sequence gives I_c(2n,3).at n=8A019531
- Convolution of natural numbers with composite numbers.at n=27A023539
- s(n+3)/2, where s is A024735.at n=11A024736
- a(n) = (d(n)-r(n))/5, where d = A026054 and r is the periodic sequence with fundamental period (3,3,0,0,4).at n=54A026056
- a(n) = n + (n+1)^2 + (n+2)^3 + (n+3)^4.at n=6A027621
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 21.at n=32A031519
- "DHK[ 7 ]" (bracelet, identity, unlabeled, 7 parts) transform of 1,1,1,1,...at n=14A032248
- Coordination sequence for lattice D*_4 (with edges defined by l_1 norm = 1).at n=11A035471
- Coordination sequence for diamond structure D^+_6. (Edges defined by l_1 norm = 1.)at n=6A035879
- Numbers having three 0's in base 9.at n=30A043455
- T(n,3), array T as in A050186; a count of aperiodic binary words.at n=33A050188
- a(n) = Product_{d|n, d^2<=n} (d+n/d); a(1)=1.at n=31A050214
- Numbers k such that sigma(x) = k has exactly 8 solutions.at n=20A060664
- Numbers k such that A069088(k) divides k.at n=26A069145
- Numbers k such that gcd(d(k^3), d(k)) is not a power of 2.at n=20A069781
- Smallest number k for which the set of solutions to phi(x) = k has 2n-1 entries.at n=17A071387