3211
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 7
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 3660
- Proper Divisor Sum (Aliquot Sum)
- 449
- 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
- 2808
- Möbius Function
- 0
- Radical
- 247
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 2
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
- 123
- 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
- Let A(n) = #{(i,j,k): i^2 + j^2 + k^2 <= n}, V(n) = (4/3)Pi*n^(3/2), P(n) = A(n) - V(n); A000092 gives values of n where |P(n)| sets a new record; sequence gives (nearest integer to, I believe) P(A000092(n)).at n=51A000223
- Numbers that are the sum of 9 positive 7th powers.at n=18A003376
- a(n) = 2*a(n-1) + a(n-2) - a(n-3), with a(0) = a(1) = 0, a(2) = 1.at n=12A006054
- Coordination sequence T2 for Zeolite Code CON.at n=40A009869
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly three 1's.at n=40A013650
- a(n) = n*(9*n-2).at n=19A013656
- a(n) = (2*n - 7)*n^2.at n=13A015242
- n written in fractional base 4/3.at n=13A024631
- Divisors = 3 (mod 4) of Descartes's 198585576189.at n=36A033871
- Number of partitions of n into parts not of form 4k+2, 12k, 12k+1 or 12k-1.at n=59A036017
- Number of partitions of n such that cn(0,5) = cn(2,5) < cn(3,5) = cn(4,5) <= cn(1,5).at n=54A036854
- 3-wave sequence starting with 1, 1, 1.at n=21A038196
- Concatenate first n nonzero Fibonacci numbers in reverse order.at n=3A038399
- a(n)=(s(n)+2)/8, where s(n)=n-th base 8 palindrome that starts with 6 (in base 8), written in decimal digits.at n=35A043070
- Numbers n such that string 1,1 occurs in the base 10 representation of n but not of n-1.at n=32A044343
- Numbers n such that string 1,1 occurs in the base 10 representation of n but not of n+1.at n=32A044724
- Has both a primitive and imprimitive representation as x^2 + xy + y^2.at n=24A045897
- House numbers (version 2): a(n) = (n+1)^3 + (n+1)*Sum_{i=0..n} i.at n=12A050509
- Expansion of e.g.f.: (1/2) - (1/2)*(5 - 4*exp(x))^(1/2).at n=5A052886
- Append n-th Fibonacci number to previous term, reverse alternate terms.at n=3A053055