6216
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 32
- Divisor Sum
- 18240
- Proper Divisor Sum (Aliquot Sum)
- 12024
- 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
- 1728
- Möbius Function
- 0
- Radical
- 1554
- Omega Function (Ω)
- 6
- Little Omega Function (ω)
- 4
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- yes
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- yes
- 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
- 36
- 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
- Sum_{i=1..(10^n - 1)/9} i, or ((10^n -1)/9)*((10^n -1)/9 +1)/2 (n-th term is the middle 2(n-1) digits of the (n+9)-th term for n > 1).at n=2A003555
- Binomial coefficient C(8n,n-12).at n=2A004393
- Expansion of 1/((1-2*x)^3*(1-x^2)^2).at n=7A011780
- arcsin(sec(x)*tan(x))=x+6/3!*x^3+120/5!*x^5+6216/7!*x^7+652800/9!*x^9...at n=3A012795
- a(n) = 2*n*(4*n - 1).at n=28A014635
- Number of ordered 5-tuples of integers from [ 1,n ] with no common factors among quadruples.at n=13A015653
- Alkane (or paraffin) numbers l(9,n).at n=11A018210
- a(n) = least m such that if r and s in {1/1, 1/3, 1/5, ..., 1/(2n-1)} satisfy r < s, then r < k/m < (k+3)/m < s for some integer k.at n=29A024844
- a(n) = (prime(n)-3)*(prime(n)-5)/8.at n=47A030007
- Numerators of continued fraction convergents to sqrt(585).at n=6A042120
- Denominators of continued fraction convergents to sqrt(871).at n=9A042683
- Numbers having four 4's in base 6.at n=16A043388
- Starting from generation 7 add previous and next term yielding generation 8.at n=14A048454
- Iterated procedure 'composite k added to sum of its prime factors reaches a prime' yields 6 skipped primes.at n=36A050773
- Expansion of (1+2*x+3*x^2)/((1-x)^3*(1-x^2)).at n=22A055232
- Number of points in N^n of norm <= 2.at n=20A055417
- Numbers which are the sum of their proper divisors containing the digit 0.at n=40A059461
- Numbers k such that sigma(x) = k has exactly 6 solutions.at n=27A060662
- Numbers k such that phi(x) = k has exactly 11 solutions.at n=19A060674
- a(n) = (prime(n)^2 - 1)/8.at n=46A061066