6641
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 6900
- Proper Divisor Sum (Aliquot Sum)
- 259
- 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
- 6384
- Möbius Function
- 1
- Radical
- 6641
- 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
- 93
- 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
- a(n) = 2*a(n-1) + a(n-4).at n=12A008999
- a(n) = floor( n*(n-1)*(n-2)*(n-3)/32 ).at n=23A011942
- Powers of fourth root of 15 rounded down.at n=13A018087
- Numbers k such that the continued fraction for sqrt(k) has period 17.at n=35A020356
- Numbers k such that k^2 is palindromic in base 3.at n=37A029984
- Divide odd numbers into groups with prime(n) elements and add together.at n=9A034960
- Number of partitions of n into parts not of the form 25k, 25k+2 or 25k-2. Also number of partitions with 1 part of size 1 and differences between parts at distance 11 are greater than 1.at n=36A036001
- Composite numbers whose prime factors contain no digits other than 2 and 9.at n=28A036313
- Denominators of continued fraction convergents to sqrt(105).at n=4A041189
- Denominators of continued fraction convergents to sqrt(357).at n=6A041677
- Denominators of continued fraction convergents to sqrt(420).at n=4A041799
- Denominators of continued fraction convergents to sqrt(919).at n=11A042777
- Denominators of continued fraction convergents to sqrt(945).at n=8A042829
- Numbers whose base-3 representation contains exactly four 0's and four 2's.at n=35A045013
- a(n)=T(n,n+3), array T as in A049735.at n=31A049743
- Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 15.at n=11A051980
- (p^2-5)/4 for odd primes p.at n=36A074367
- a(n) = A077347(n)^(1/2).at n=43A077349
- a(n) = 4*n^2 + 6*n + 1.at n=40A082108
- Semiprimes that are the sum of two positive cubes. Common terms of A003325 and A046315.at n=30A085366