6605
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 7932
- Proper Divisor Sum (Aliquot Sum)
- 1327
- 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
- 5280
- Möbius Function
- 1
- Radical
- 6605
- Omega Function (Ω)
- 2
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 137
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- 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
- Generalized Catalan Numbers x^4*A(x)^2 -(1-x+x^4+x^5+x^6+x^7)*A(x) + 1 =0.at n=24A023430
- a(n) = least m such that if r and s in {1/2, 1/4, 1/6, ..., 1/2n} satisfy r < s, then r < k/m < (k+4)/m < s for some integer k.at n=26A024848
- Expansion of (1-x)^(-1)/(1+2*x^2+2*x^3).at n=19A077895
- a(n) = 10*n^2 - 6*n + 1.at n=25A087348
- Positions of high-water marks of A118421.at n=41A118423
- Triangle, T(n, k) = coefficients [x^k]( p(x,n) ), where p(x, n) = (x+1)^n for n < 2, otherwise (x+1)^n + x*((1+x)^(n-2) + 2^(n-2)*(1-x)^(n-1)*LerchPhi(x, 2-n, 1/2)), read by rows.at n=57A147566
- Triangle, T(n, k) = coefficients [x^k]( p(x,n) ), where p(x, n) = (x+1)^n for n < 2, otherwise (x+1)^n + x*((1+x)^(n-2) + 2^(n-2)*(1-x)^(n-1)*LerchPhi(x, 2-n, 1/2)), read by rows.at n=63A147566
- 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, 0, 1), (-1, 1, 0), (1, -1, 1), (1, 0, 0), (1, 1, -1)}.at n=8A148749
- Triangle of coefficients of polynomials u(n,x) jointly generated with A209169; see the Formula section.at n=41A209168
- Number of partitions of n+7 with largest inscribed rectangle having area <= n.at n=24A218628
- Positions of even terms of A050376.at n=4A228776
- Number of partitions p of n such that median(p) = multiplicity(max(p)).at n=38A240209
- A046802(x,y) --> A046802(x,y+1), transform of e.g.f. for the graded number of positroids of the totally nonnegative Grassmannians G+(k,n); enumerates faces of the stellahedra.at n=23A248727
- Number of strings of length n over a 5-letter alphabet that begin with a nontrivial palindrome.at n=6A249638
- Numbers n such that the Crandall number C = A262961(n) has exactly one prime divisor p >= n/2.at n=14A265079
- Coefficient of x^2 in minimal polynomial of the continued fraction [1^n,2/3,1,1,1,...], where 1^n means n ones.at n=9A266703
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 84", based on the 5-celled von Neumann neighborhood.at n=33A270106
- Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 627", based on the 5-celled von Neumann neighborhood.at n=45A273274
- a(n) is the index of the first occurrence of n in A166006.at n=8A278737
- a(n) = A292136(n)^2 + A292137(n)^2.at n=49A292464