7281
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
- 6
- Divisor Sum
- 10530
- Proper Divisor Sum (Aliquot Sum)
- 3249
- 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
- 4848
- Möbius Function
- 0
- Radical
- 2427
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 2
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
- 18
- 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
- a(n) = floor(2^(n-1)/n).at n=17A006788
- 4-dimensional centered tetrahedral numbers.at n=13A008498
- Pseudoprimes to base 44.at n=40A020172
- Numbers k such that the continued fraction for sqrt(k) has period 92.at n=13A020431
- a(n) = Sum_{k=0..2n} (k+1) * A027113(n, 2n-k).at n=7A027138
- Multiplicity of highest weight (or singular) vectors associated with character chi_98 of Monster module.at n=41A034486
- Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,3,0.at n=6A037597
- Inverse Moebius transform of A000048 (starting at term 0).at n=18A054172
- a(n) = a(n-1) + 2*a(floor(n/2)) if n > 0, otherwise 1.at n=24A058039
- Duplicate of A006788.at n=17A074099
- Numbers n with property that n is not a power of 2 and the finite sequence n, f(n), f(f(n)), ...., 1 in the Collatz (or 3x + 1) problem contains exactly one prime. (The earliest "1" is meant.)at n=37A078440
- Number of permutations on n letters without double falls and without initial falls.at n=8A080635
- a(n) = n*(n^2+3*n-1)/3.at n=27A084990
- a(n) = Sum{k=0..n} binomial(n,k)^2*C(k), where C() = A000108() are the Catalan numbers.at n=6A086618
- Sum(j=1,n,floor(A000041(j)/j)).at n=40A086736
- a(n) = Sum_{i+j+k=n, 0<=i<=n, 0<=j<=n, 0<=k<=n} (n+i+j)!/((i+j)! * j! * k!).at n=4A092471
- a(n) = a(n-1) + 2^(A047258(n)) for n>1, a(1)=1.at n=6A113867
- Numbers m such that greatest prime divisor of (m-th prime + 1) is 3.at n=26A121820
- Numbers such that the sum of the factorials of the digits of the fifth power is a square.at n=12A126078
- a(0)=0. a(n) = a(n-1) + sum of positive integers which are <= n and not part of the sequence.at n=36A129694