6665
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
- 8
- Divisor Sum
- 8448
- Proper Divisor Sum (Aliquot Sum)
- 1783
- 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
- 5040
- Möbius Function
- -1
- Radical
- 6665
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 93
- 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
- no
- Odd
- yes
Appears in sequences
- Centered tetrahedral numbers.at n=21A005894
- a(n) = 5*a(n-1) + 6*a(n-2), a(0) = 0, a(1) = 1.at n=6A015540
- Pseudoprimes to base 94.at n=44A020222
- Expansion of (1-x^8)*(1+x^5)/(1-x^2)^5.at n=42A027635
- Expansion of (1-x^8)*(1+x^5)/(1-x^2)^5.at n=47A027635
- a(n) = (n^7 - n)/42.at n=6A030180
- Expansion of Molien series for 4-D extraspecial group 2^{1+2*2}.at n=42A030533
- Numbers k such that k^2 contains only digits {2,4,5}.at n=9A031154
- Numbers k such that if d,e are consecutive digits of k in base 6, then |d-e| >= 4.at n=40A032988
- Numerators of continued fraction convergents to sqrt(694).at n=6A042334
- Base-6 palindromes that start with 5.at n=19A043014
- Numbers having three 6's in base 10.at n=23A043515
- Numbers whose base-9 representation has exactly 5 runs.at n=12A043634
- a(n)=T(2n-1,n), array T given by A048212.at n=42A048221
- Beastly (or hateful) numbers: numbers containing the string 666 in their decimal expansion.at n=11A051003
- Periodic points under the map A053392 that adds consecutive pairs of digits and concatenates them.at n=20A053393
- Number of 6-ary Lyndon words with trace 0 mod 6.at n=6A054665
- Number of 6-ary Lyndon words with trace 1 mod 6.at n=6A054666
- Number of 6-ary Lyndon words with trace 2 mod 6.at n=6A054667
- Number of 6-ary Lyndon words with trace 3 mod 6.at n=6A054700