16666
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 25
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 26964
- Proper Divisor Sum (Aliquot Sum)
- 10298
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7680
- Möbius Function
- -1
- Radical
- 16666
- 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
- 128
- 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
- Numbers whose maximal base-10 run length is 4.at n=23A033285
- a(n) = floor(10^5/n).at n=5A033427
- Numbers having four 6's in base 10.at n=1A043516
- Beastly (or hateful) numbers: numbers containing the string 666 in their decimal expansion.at n=31A051003
- a(n) = floor(10^(n-1)/n).at n=5A056159
- Result of left concatenation of the next Roman-numeral symbol.at n=8A118640
- Numbers k such that 2^k == 10 (mod k).at n=4A128123
- Numbers k such that k and k^2 use only the digits 1, 2, 5, 6 and 7.at n=39A137004
- Number of numbers removed in each step of Eratosthenes's sieve for 10^5.at n=1A145538
- Fourth powers (n * n * n * n) in carryless arithmetic mod 10.at n=14A169886
- Fourth powers (n * n * n * n) in carryless arithmetic mod 10.at n=32A169886
- Numbers n such that (n+n+1) divides the decimal concatenation [n, n+1].at n=8A173712
- Number of n X n binary matrices with rows and columns each in strictly increasing order as binary numbers and no 1 neighboring another 1.at n=7A180996
- Triangle of coefficients of polynomials u(n,x) jointly generated with A210738; see the Formula section.at n=49A210603
- Number of partitions of n having population standard deviation < 2.at n=46A238658
- Number of partitions of n having standard deviation σ <= 2.at n=46A238659
- a(n) = (5*10^n - 2)/3.at n=4A246057
- Numbers which are divisible by prime(d) for all digits d in their decimal representation.at n=35A256786
- Number of maximal cubefree binary words of length n.at n=33A282133
- Numbers k such that the decimal expansion of the sum of the reciprocals of the digits of k starts with the digits of k in the same order.at n=6A354466