2666
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
- 8
- Divisor Sum
- 4224
- Proper Divisor Sum (Aliquot Sum)
- 1558
- 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
- 1260
- Möbius Function
- -1
- Radical
- 2666
- 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
- 115
- 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
- Number of n-node rooted trees of height 4.at n=12A000299
- Numbers k such that 4!*(2k-5)!/(k!*(k-1)!) is an integer.at n=21A004784
- 5!(2n-6)!/n!(n-1)! is an integer.at n=26A004785
- Number of n-step spirals on hexagonal lattice.at n=12A006778
- Number of factors in the infinite word formed by the Kolakoski sequence A000002.at n=52A007782
- If a, b in sequence, so is ab+6.at n=30A009307
- Number of trees on n nodes with forbidden limbs.at n=9A014274
- Numbers n such that phi(n) * sigma(n) + 9 is a perfect square.at n=33A015728
- Nine iterations of Reverse and Add are needed to reach a palindrome.at n=10A015990
- Expansion of 1/(1-x^10-x^11-x^12-x^13-x^14-x^15-x^16-x^17-x^18-x^19-x^20).at n=62A017896
- Conjectured formula for irreducible 6-fold Euler sums of weight 2n+16.at n=18A019459
- Numbers in which all pairs of consecutive base-6 digits differ by 2.at n=40A033084
- Coordination sequence T4 for Zeolite Code CFI.at n=34A033602
- Numbers for which the sum of reciprocals of digits is an integer.at n=45A034708
- Number of partitions of n such that cn(0,5) = cn(2,5) <= cn(1,5) <= cn(3,5) = cn(4,5).at n=63A036848
- Numbers whose sum of reciprocals of digits is the reciprocal of an integer.at n=31A037264
- Sum of reciprocals of digits = 1.at n=13A037268
- Coordination sequence T2 for Zeolite Code SFF.at n=34A038438
- Base-6 palindromes that start with 2.at n=16A043011
- a(n)=(s(n)+3)/8, where s(n)=n-th base 8 palindrome that starts with 5.at n=31A043069