6845
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 23
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 8442
- Proper Divisor Sum (Aliquot Sum)
- 1597
- 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
- 5328
- Möbius Function
- 0
- Radical
- 185
- 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
- 150
- 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
- tan(arcsin(tan(x))) = x+5/3!*x^3+121/5!*x^5+6845/7!*x^7+698161/9!*x^9...at n=3A012077
- Expansion of e.g.f. exp(arctanh(tan(x))).at n=7A012259
- Numbers k such that the continued fraction for sqrt(k) has period 19.at n=39A020358
- a(n) = least m such that if r and s in {1/2, 1/4, 1/6, ..., 1/(2*n)} satisfy r < s, then r < k/m < (k+3)/m < s for some integer k.at n=30A024845
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 14.at n=7A031602
- a(n) = 5*n^2.at n=37A033429
- Number of partitions of n such that cn(0,5) = cn(2,5) <= cn(3,5) = cn(4,5) <= cn(1,5).at n=55A036846
- Denominators of continued fraction convergents to sqrt(387).at n=6A041735
- a(n)=T(n,n), array T as in A049735.at n=33A049740
- Number of bracelet structures using exactly four different colored beads.at n=10A056359
- Number of primitive (period n) bracelet structures using exactly four different colored beads.at n=10A056368
- Numbers n such that 1n1, 3n3, 7n7 and 9n9 are all primes.at n=15A059677
- Numbers from A066112 that are neither square nor twice a square, i.e., are not in A028982 but are in A028983.at n=25A066134
- Numbers k such that sigma(core(k)) = tau(k) where core(k) is the squarefree part of k, tau(k) is the number of divisors of k, and sigma(k) is their sum.at n=41A069827
- Numbers k such that the numerator of Bernoulli(2k) is divisible by the square of 37, the first irregular prime.at n=25A092230
- a(n) = Sum_{k=0..floor(n/2)} binomial(n,2*k)*Fibonacci(k+1).at n=12A101891
- a(n) = 8*n^2 + 4*n + 1.at n=29A102083
- a(n) = {n^2}_n.at n=28A122635
- Connell (3,5)-sum sequence (partial sums of the (3,5)-Connell sequence).at n=69A122796
- Number of subsets {x(1),x(2),...,x(k)} of {1,2,...,n} such that all differences |x(i)-x(j)| are distinct.at n=20A143823