6805
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
- 8172
- Proper Divisor Sum (Aliquot Sum)
- 1367
- 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
- 5440
- Möbius Function
- 1
- Radical
- 6805
- 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
- 62
- 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
- n written in fractional base 10/6.at n=55A024661
- Smallest k>1 such that k(p-1)-1 is divisible by p^2, p=n-th prime.at n=22A039914
- Denominators of continued fraction convergents to sqrt(85).at n=8A041151
- Denominators of continued fraction convergents to sqrt(340).at n=12A041643
- Denominators of continued fraction convergents to sqrt(765).at n=8A042475
- Base-9 palindromes that start with 1.at n=23A043028
- Numbers whose base-4 representation contains exactly four 1's and three 2's.at n=19A045108
- a(n) = n^4 + 3*n^2 + 1.at n=9A057721
- Centered 18-gonal numbers.at n=27A069131
- Numbers generated by the Fibonacci polynomial x^4 + 3x^2 + 1.at n=8A085151
- Maximal values in A038598.at n=43A093330
- Number of A095282-primes in range ]2^n,2^(n+1)].at n=17A095292
- First differences of Chebyshev polynomials S(n,83) = A097839(n) with Diophantine property.at n=2A097841
- Expansion of g.f.: x/(1 - 9*x - x^2).at n=5A099371
- Numbers of the form k^2 - k - 1 whose digit sum is also a number of the form k^2 - k - 1.at n=31A117746
- p^2-p-1 that is not prime, where p is prime.at n=11A119609
- Integers of the form c(n)/b(n) where c(n+1)=c(n)+(n+1)^4 with c(0)=1 and b(n+1)=b(n)+(n+1)^2 with b(0)=1.at n=42A119617
- a(n) = 4*n^2 - 6*n + 1.at n=41A125202
- Integers of the form (p(n+1)*p(n) - 1)/(p(n+1) - p(n)) where p(n) denotes the n-th prime.at n=42A128490
- a(n) = 15*n^2 + 9*n + 1.at n=21A134153