13475
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 18
- Divisor Sum
- 21204
- Proper Divisor Sum (Aliquot Sum)
- 7729
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8400
- Möbius Function
- 0
- Radical
- 385
- Omega Function (Ω)
- 5
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 182
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- Logarithmic transform of Fibonacci numbers.at n=10A007553
- Coordination sequence for Ni2In, Position Ni1 and In.at n=35A009941
- Fibonacci sequence beginning 5, 19.at n=15A022143
- a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n-k+1), where k = floor(n/2), s = natural numbers, t = odd natural numbers.at n=41A024862
- a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is a nonnegative integer, s(0) = 0, s(1) = 1, s(n) = 4, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-4), where T is the array defined in A026105.at n=8A026110
- Numbers whose prime factors are in {5, 7, 11}.at n=40A036490
- Transformation of A036490: 5^a*7^b*11^c -> 5^a*7^floor((b+2)/2)*11^c.at n=40A036491
- Odd composite numbers divisible by the sum of their prime factors (counted with multiplicity).at n=40A046347
- a(n) = Sum_{k=1..floor(n/2)} T(n, 2k), array T as in A049777.at n=41A049779
- a(n) is the cototient of n^3.at n=34A053192
- Composite numbers k with no prime factor among (2, 3) (cf. A038509) and such that phi(k) < 2*k/3.at n=39A069043
- Fifth column of the (1,4)-Pascal triangle A095666.at n=19A095667
- Denominator of Sum_{k=0..n} 1/binomial(n,k)^2.at n=11A100517
- a(n) equals the (n*(n+1)/2)-th partial sum of the self-convolution cube of A010054, which has the g.f.: Sum_{k>=0} x^(k*(k+1)/2).at n=29A109414
- a(n) is the smallest positive integer that is coprime to n and has n divisors.at n=17A136641
- Numbers of the form 49*k, where 49*k+2 and 49*k-6 are both prime.at n=5A153779
- Eleven times hexagonal numbers: a(n) = 11*n*(2*n-1).at n=25A154617
- Denominator of Laguerre(n, -12).at n=14A160555
- Number of peak plateaux in all Dyck paths of semilength n with no UUU's and no DDD's (U=(1,1), D=(1,-1)).at n=13A166287
- Exponential Riordan array (e^(x), x*A000108(x)).at n=32A185946