6618
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 13248
- Proper Divisor Sum (Aliquot Sum)
- 6630
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 2204
- Möbius Function
- -1
- Radical
- 6618
- Omega Function (Ω)
- 3
- 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
- 44
- 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
- a(n) = Sum{T(i,j)}, 0<=i<=n, 0<=j<=n, T given by A026703.at n=10A026712
- Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 24.at n=36A051989
- Numbers which are the sum of their proper divisors containing the digit 0.at n=43A059461
- Coefficient of q^1 in nu(n), where nu(0)=1, nu(1)=b and, for n>=2, nu(n)=b*nu(n-1)+lambda*(1+q+q^2+...+q^(n-2))*nu(n-2) with (b,lambda)=(3,1).at n=8A074361
- Left truncatable 3-almost primes, in which repeatedly deleting the leftmost digit gives a 3-almost prime at every step until a single-digit 3-almost prime remains.at n=41A085248
- a(1)= 10000, a(2)= 10000; for n>2, a(n)= ( a(n-2) + a(n-1) ) (mod 20000).at n=33A096973
- Expansion of (1-2*x^2)/((1-2*x)*(1+x-x^2)).at n=14A099163
- Number of rooted identity trees with n generators.at n=10A108523
- a(0)=1; for n > 0, a(n) = a(n-1) + a(prime(n)(mod n)), where prime(n) is the n-th prime.at n=35A127066
- Inrepfigit (INverse REPetitive FIbonacci-like diGIT) numbers (or Htiek numbers).at n=10A128546
- Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 00100-11111-00100 pattern in any orientation.at n=19A147007
- a(n) = 6*(24*n - 1).at n=45A187206
- Expansion of (G(-x) / chi(-x))^2 in powers of x where chi() is a Ramanujan theta function and G() is a Rogers-Ramanujan function.at n=26A261866
- Number of length n arrays of permutations of 0..n-1 with each element moved by -5 to 5 places and exactly two more elements moved upwards than downwards.at n=8A263784
- Numbers n whose Zeckendorf representation is of the form ww, for w a nonempty block of digits.at n=52A286710
- Consider the digit reverse of a number x. Take the sum of these digits and repeat the process deleting the first addend and adding the previous sum. The sequence lists the numbers that after some iterations reach a sum equal to x.at n=20A289868
- Number of n element multisets of the 12th roots of unity with zero sum.at n=18A321417
- Indices k of Gram points g(k) for successive negative maximal values of the Riemann zeta function on the critical line.at n=14A325932
- Indices n of j-points j(n) for successive positive maxima of the Riemann zeta function on critical line.at n=24A327546
- Number of compositions (ordered partitions) of n into an odd number of distinct primes.at n=60A339433