3820
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
- 12
- Divisor Sum
- 8064
- Proper Divisor Sum (Aliquot Sum)
- 4244
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 1520
- Möbius Function
- 0
- Radical
- 1910
- Omega Function (Ω)
- 4
- 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
- 30
- 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
- yes
- Odd
- no
Appears in sequences
- a(n) = (n+1)*(n^2+n+2)/2; g.f.: (1 + 2*x^2) / (1 - x)^4.at n=19A006000
- Exponential self-convolution of numbers of trees on n nodes.at n=9A006771
- a(n) = F(n) + L(n) + n, where F(n) (A000045) and L(n) (A000204) are Fibonacci and Lucas numbers respectively.at n=16A013915
- a(n) = Fibonacci(n) - n^2.at n=19A014283
- Number of lines through exactly 5 points of an n X n grid of points.at n=33A018812
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite MTW = ZSM-12 Nan[AlnSi28-nO56] starting with a T2 atom.at n=11A019198
- a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2), t = A000045 (Fibonacci numbers).at n=14A023860
- a(n) = floor((3rd elementary symmetric function of 2,3,...,n+3)/(2+3+...+n+3)).at n=14A024178
- Number of different products of partitions of n; number of partitions of n into prime parts (1 included); number of distinct orders of Abelian subgroups of symmetric group S_n.at n=43A034891
- a(n) = T(2n-1,n), array T given by A048201.at n=31A048208
- 22-gonal numbers: a(n) = n*(10*n-9).at n=20A051874
- Number of positive integers <= 2^n of form 4 x^2 + 5 y^2.at n=15A054169
- Numbers n such that n^1024 + 1 is prime (a generalized Fermat prime).at n=9A057002
- The array of A063179 read by diagonals in direction of creation.at n=41A063180
- The array of A063179 read by diagonals in the 'up' direction.at n=39A063181
- Numbers k such that phi(sigma(k^3)) is a square.at n=46A063796
- The least k such that A063994(k) = Product_{primes p dividing k} gcd(p-1, k-1) = n, or 0 if there's no such k.at n=18A064234
- Numbers k such that S(k+2) = d(k)+2, where S(k) is the Kempner function (A002034) and d(k) is the number of divisors of k (A000005).at n=26A073535
- Difference between the sum of next prime(n) natural numbers and the sum of next n primes.at n=13A082749
- G.f. A(x) satisfies: A(x) = 1/(1-2*x) + x^2*A(x)^2.at n=9A086622