3905
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- 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)
- 1279
- 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
- 2800
- Möbius Function
- -1
- Radical
- 3905
- 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
- 100
- 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) = 8*a(n-1) - a(n-2); a(0) = 0, a(1) = 1.at n=5A001090
- Expansion of Product_{k>=1} (1 - x^k)^11.at n=28A010819
- Numbers k that divide s(k), where s(1)=1, s(j)=5*s(j-1)+j.at n=5A014852
- Powers of fourth root of 7 rounded down.at n=17A018063
- Powers of fourth root of 7 rounded to nearest integer.at n=17A018064
- a(n) = 4th Chebyshev polynomial (second kind) evaluated at 2^n.at n=2A020541
- a(n) = Sum_{k=1..n} n^k.at n=5A031972
- Good sequence of increments for Shell sort (best on big values).at n=9A033622
- Sums of 5 distinct powers of 5.at n=5A038477
- Denominators of continued fraction convergents to sqrt(15).at n=9A041023
- Denominators of continued fraction convergents to sqrt(60).at n=9A041105
- Denominators of continued fraction convergents to sqrt(135).at n=13A041247
- Starting positions of strings of 2 4's in the decimal expansion of Pi.at n=41A050230
- Period of the sequence of Bell numbers A000110 (mod n).at n=24A054767
- a(n) = n^4 - 3*n^2 + 1.at n=8A057722
- Numbers k such that the Lucas Aurifeuillian primitive part A of Lucas(k) is prime.at n=37A061442
- Table by antidiagonals of T(n,k)=n*T(n,k-1)-T(n,k-2) starting with T(n,1)=1.at n=73A073134
- a(n) = Sum_{d|n} (2^(n-d)).at n=11A074854
- Least positive integer multiples of angle x such that their direction cosines form a unit vector: Sum_{k>0} cos(a(k)*x)^2 = 1, where a(1)=1, a(n+1)>a(n) and x=3-Pi/2.at n=19A080139
- Greedy frac multiples of 1/Pi: a(1)=1, Sum_{n>0} frac(a(n)*x) = 1 at x=1/Pi, where "frac(y)" denotes the fractional part of y.at n=17A080142