6489
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 10816
- Proper Divisor Sum (Aliquot Sum)
- 4327
- 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
- 3672
- Möbius Function
- 0
- Radical
- 2163
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 3
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
- 49
- 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
- Number of permutations of length n with 2 consecutive ascending pairs.at n=7A000274
- Number of partitions of n into parts of sizes {a( )} is a(n).at n=49A007209
- Triangle read by rows: T(n,k) is the number of permutations of [n] having k consecutive ascending pairs (0 <= k <= n-1).at n=33A010027
- Number of partitions satisfying cn(0,5) <= cn(1,5) + cn(2,5) + cn(3,5) and cn(0,5) <= cn(4,5) + cn(2,5) + cn(3,5).at n=31A039845
- Numbers with more than one factorization into S-primes. See A054520 and A057948 for definition.at n=40A057949
- Numbers primitive with respect to having more than one factorization into S-primes. See related sequences for definition.at n=33A057950
- a(n) = a(n-1) + a(n - 1 minus the number of terms of a(k) == n (mod 3) so far).at n=34A060730
- Nonprime numbers n such that the GCD of n and the Chowla's function of n (A048050) is >= n/3.at n=5A066924
- z such that the Diophantine equation x^3+y^4=z^3 has solutions.at n=43A070741
- Least k such that Sum_{i=1..k} 1/phi(i) >= n.at n=16A074467
- Largest difference between consecutive divisors of n is equal to the sum of divisors of n except 1 and n.at n=2A074844
- Pair the odd numbers such that the k-th pair is (r, r+2k) where r is the smallest odd number not included earlier: (1, 3), (5, 9), (7, 13), (11, 19), (15, 25), (17, 29), (21, 35), (23, 39), (27, 45), ... This is the sequence of the product of the members of pairs.at n=19A075320
- Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=3, r=3, I={-1,0,1,2}.at n=39A079982
- Numbers k such that 7*5^k + 2 is a prime.at n=9A083092
- A014486-indices of symmetric binary trees.at n=23A083940
- Least k such that 10^(2n-1)+k is a brilliant number.at n=45A084476
- Greater of a,b where n^2 = a^3 + b^3; a,b>0 and gcd(a,b)=1. The lesser of a,b is the corresponding term in A099532 and n, which is used to order this sequence, is the corresponding term in A099426.at n=21A099533
- a(n) = Sum_{i=1..n} (n-i+1)*phi(i).at n=39A103116
- Triangle read by rows: T(n,k) is the number of permutations of [n] having k small descents (n >= 1; 0 <= k <= n-1). A small descent in a permutation (x_1,x_2,...,x_n) is a position i such that x_i - x_(i+1) = 1.at n=30A123513
- Partial sums of A130237.at n=40A130238