8218
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 14112
- Proper Divisor Sum (Aliquot Sum)
- 5894
- 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
- 3516
- Möbius Function
- -1
- Radical
- 8218
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 39
- 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
- yes
- Odd
- no
Appears in sequences
- Number of n-digit reversible primes (or emirps) with distinct digits.at n=7A003684
- Expansion of cosh(tan(x).exp(x)).at n=7A009162
- Fibonacci sequence beginning 4, 11.at n=15A022131
- a(n) = n*(21*n-1)/2.at n=28A022278
- Expansion of 1/((1-x)*(1-6*x)*(1-9*x)*(1-12*x)).at n=3A024347
- a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5, with initial values 1,2,1,1.at n=10A025270
- a(n) = (d(n)-r(n))/2, where d = A026060 and r is the periodic sequence with fundamental period (1,0,0,0).at n=37A026061
- Numbers whose base-4 representation contains exactly three 0's and three 2's.at n=30A045055
- Pisot sequence L(4,9).at n=9A048582
- a(0)=0; for n>0, a(n) = Sum_{d|n} d*2^(n/d).at n=13A054598
- Sum_{d|n, d odd} d*2^(n/d).at n=13A054600
- Number of 2 X n 0-1 matrices avoiding simultaneously the right angled numbered polyomino patterns (ranpp) (00;1), (01;0), (10;0) and (01;1).at n=13A100314
- Bond series for second parallel moment of hexagonal net.at n=11A120543
- Lesser of twin simili-primes of order 2.at n=31A126699
- Duplicate of A100314.at n=13A131831
- Numbers m for which Sum_digits(m!) is a multiple of Sum_digits(m!!).at n=43A135206
- Perfect numbers written backwards.at n=3A135624
- a(n) = prime(prime(A028815(n) - 1) - 1) - 1.at n=40A141136
- a(n) = 686*n - 14.at n=11A157363
- Numbers n such that 2^x + 3^y is never prime when max(x,y) = n.at n=12A159625