6662
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9996
- Proper Divisor Sum (Aliquot Sum)
- 3334
- 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
- 3330
- Möbius Function
- 1
- Radical
- 6662
- 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
- 181
- 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
- yes
- Odd
- no
Appears in sequences
- Numbers k such that phi(k + 4) | sigma(k) + 4.at n=9A015870
- Nine iterations of Reverse and Add are needed to reach a palindrome.at n=42A015990
- a(n) = Sum_{i=1..floor((n+1)/4)} a(2*i-1) * a(n-2*i+1), with a(1)=a(2)=1.at n=23A024722
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 80.at n=17A031578
- Sum of reciprocals of digits = 1.at n=40A037268
- Positive numbers having the same set of digits in base 4 and base 9.at n=29A037427
- Numbers having three 6's in base 10.at n=20A043515
- Beastly (or hateful) numbers: numbers containing the string 666 in their decimal expansion.at n=8A051003
- McKay-Thompson series of class 39A for Monster.at n=42A058659
- Harmonic mean of digits is 4.at n=42A062182
- Number of 3-dimensional polyominoes (or polycubes) with n cells and trivial rotational symmetry group.at n=7A066453
- Decimal concatenations of the quadruples (d1,d2,d3,d4) with elements in {2,4,6} for which there exists a prime p >= 5 such that the differences between the 5 consecutive primes starting with p are (d1,d2,d3,d4).at n=24A078868
- Near-repdigit semiprimes with 6 as repeated digit.at n=14A105987
- a(n) is the largest base-7 string such that the n-th number coprime to 7 does not divide any substring of a(n).at n=3A114909
- Numbers n such that sigma(n) - phi(n) is a repdigit greater than 2.at n=32A116020
- Numbers n whose reverse binary representation has the following property: let a 0 mean "halving" and a 1 mean "k -> 3k+1". The number describes an operation k -> f_n(k). If the equation f_n(k) = k has a positive integer solution, n is a term in the sequence.at n=38A125756
- Numbers k such that k and k^2 use only the digits 2, 3, 4, 6 and 8.at n=13A137072
- a(n) = 4*a(n-1) - 3*a(n-2) + 2*a(n-3) - 1*a(n-4).at n=10A138747
- a(n) = 3*A146085(n) - 1.at n=32A146087
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, -1), (0, 1, 1), (1, -1, 0)}.at n=10A148173