8605
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 10332
- Proper Divisor Sum (Aliquot Sum)
- 1727
- 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
- 6880
- Möbius Function
- 1
- Radical
- 8605
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 109
- 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
- Coefficient of x^n in (Product_{m=1..n}(1-x^m))^n.at n=13A008705
- Expansion of Product_{k>=1} (1 - x^k)^13.at n=13A010820
- Number of squares on infinite chessboard at <= n knight's moves from a fixed square.at n=25A018836
- a(n) = (d(n) - r(n))/5, where d = A026037 and r is the periodic sequence with fundamental period (1,2,0,2,0).at n=48A026039
- Becomes prime or 4 after exactly 8 iterations of f(x) = sum of prime factors of x.at n=30A048130
- Digitally balanced numbers in both bases 2 and 3.at n=16A049361
- Average of four successive primes squared, (prime(n)^2 + prime(n+1)^2 + prime(n+2)^2 + prime(n+3)^2)/4, n>=2.at n=21A075894
- a(1) = 4, a(n+1) is the largest composite number < 2a(n).at n=12A076995
- Half-indexed Fibonacci numbers a(n)=round(sqrt((1+sqrt(5))/2)^n/sqrt(5)) a(2n)=F(n)=A000045, so a(n)=F(n/2).at n=40A127217
- First occurrence of n in A085068.at n=19A129377
- Expansion of 1/(x^k*(1-x-3*x^(k+1))) for k=6.at n=24A143457
- Generalized Fibonacci numbers Fib(n + 0.5) rounded to an integer.at n=20A158510
- Number of binary strings of length n with no substrings equal to 0001 or 0110.at n=16A164396
- a(n) = Least i in range [A165583(n),A165583(n+1)] for which abs(A165582(i)) gets the maximum value in that range.at n=39A165584
- Triangle T(n,k) = A008292(n+1,k+1) + A176487(n,k) - 1, 0<=k<=n.at n=30A176488
- Triangle T(n,k) = A008292(n+1,k+1) + A176487(n,k) - 1, 0<=k<=n.at n=33A176488
- The continued fraction of the constant r > sqrt(3) such that the partial quotients equal the integer floor of the powers of r.at n=16A227233
- Values of n such that L(18) and N(18) are both prime, where L(k) = (n^2+n+1)*2^(2*k) + (2*n+1)*2^k + 1, N(k) = (n^2+n+1)*2^k + n.at n=20A227521
- T(n,k)=Number of length n+4 0..k arrays with every five consecutive terms having four times some element equal to the sum of the remaining four.at n=37A249656
- Number of length 2+4 0..n arrays with every five consecutive terms having four times some element equal to the sum of the remaining four.at n=7A249658