4081
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 5184
- Proper Divisor Sum (Aliquot Sum)
- 1103
- 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
- 3120
- Möbius Function
- -1
- Radical
- 4081
- 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
- 51
- 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
- a(n) = n * (2*n - 1)!! - Sum_{k=0..n-1} a(k) * (2*n - 2*k - 1)!!.at n=4A004208
- Orders of cyclotomic polynomials containing a coefficient the absolute value of which is >= 4.at n=23A013592
- Expansion of 1/((1-3*x)*(1-4*x)*(1-5*x)).at n=4A016753
- Pseudoprimes to base 23.at n=34A020151
- Pseudoprimes to base 30.at n=28A020158
- Pseudoprimes to base 52.at n=18A020180
- Pseudoprimes to base 54.at n=21A020182
- Pseudoprimes to base 76.at n=45A020204
- Pseudoprimes to base 83.at n=36A020211
- Strong pseudoprimes to base 52.at n=5A020278
- Sequence satisfies T(a)=a, where T is defined below.at n=47A027597
- Lucky numbers with size of gaps equal to 14 (lower terms).at n=16A031896
- "BGK" (reversible, element, unlabeled) transform of 1,3,5,7,...at n=10A032064
- Number of different words that can be formed from an n X n grid of letters, reading horizontally, vertically or diagonally.at n=10A034720
- Number of partitions satisfying cn(1,5) <= cn(2,5) + cn(3,5) and cn(4,5) <= cn(2,5) + cn(3,5).at n=31A039890
- Denominators of continued fraction convergents to sqrt(985).at n=8A042907
- a(n)=(s(n)+6)/10, where s(n)=n-th base 10 palindrome that starts with 4.at n=30A043083
- Expansion of 1/((1-x)*(1-x^2)^2*(1-x^3)^2*(1-x^4)^2*(1-x^5)*(1-x^6)).at n=22A045513
- Upper members of a "good pair" of the form (k, 2*k +- 1).at n=28A046862
- Odd numbers seen in decimal expansion of Pi (disregarding the decimal period) contiguous, smallest and distinct.at n=40A050817