6890
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
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 13608
- Proper Divisor Sum (Aliquot Sum)
- 6718
- 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
- 2496
- Möbius Function
- 1
- Radical
- 6890
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- 106
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Expansion of Product_{k>=1} (1 - x^k)^16.at n=8A000739
- Josephus problem: numbers m such that, when m people are arranged on a circle and numbered 1 through m, the final survivor when we remove every 4th person is one of the first three people.at n=25A005427
- Numbers that are the sum of 2 nonzero squares in exactly 4 ways.at n=36A025287
- Numbers that are the sum of 2 nonzero squares in 4 or more ways.at n=37A025295
- Numbers that are the sum of 2 distinct nonzero squares in exactly 4 ways.at n=36A025305
- Numbers that are the sum of 2 distinct nonzero squares in 4 or more ways.at n=37A025314
- Shifts left 2 places under "BHK" (reversible, identity, unlabeled) transform.at n=14A032104
- Sort then Add, a(1)=19.at n=11A033900
- Number of partitions of n with equal number of parts congruent to each of 0, 2 and 3 (mod 5).at n=51A035575
- Number of partitions of n into parts not of the form 9k, 9k+2 or 9k-2. Also number of partitions with 1 part of size 1 and differences between parts at distance 3 are greater than 1.at n=42A035941
- a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = 2*n - 2 - 2^(p+1) and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = 1 and a(3) = 4.at n=15A049899
- a(n) = a(1) + a(2) + ... + a(n-1) + a(m) for n >= 4, where m = n - 1 - 2^p and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1, a(2) = 3, and a(3) = 1.at n=13A049966
- Maximal term in trajectory of P under the 'Px+1' map, where P = n-th prime, or -1 if no such term exists.at n=21A057689
- Dimension of the space of weight n cuspidal newforms for Gamma_1( 87 ).at n=33A063360
- a(n) = prime(n)^2 + 1.at n=22A066872
- Numbers k such that sigma_k(k)/k is an integer, where sigma_k(k) is the sum of the k-th powers of the divisors of k (A023887).at n=46A067313
- Centered square numbers: a(n) = 4*n^2 + 4*n + 2.at n=41A069894
- Numbers n such that [A070080(n), A070081(n), A070082(n)] is an acute integer triangle with integer area.at n=19A070146
- Sum(((-1)^k*binomial(4*n,k)),k=n..2*n).at n=4A070808
- a(1) = 1 and a(n) = ceiling((Sum_{k=1..n-1} a(k))/3) for n >= 2.at n=33A072493