8408
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 15780
- Proper Divisor Sum (Aliquot Sum)
- 7372
- 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
- 4200
- Möbius Function
- 0
- Radical
- 2102
- Omega Function (Ω)
- 4
- 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
- 96
- 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
- Tetranacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4), with a(0)=a(1)=0, a(2)=1, a(3)=2.at n=16A001630
- Coordination sequence for CaF2(2), Ca position.at n=41A009926
- Coordination sequence for MgZn2, Position Zn2.at n=23A009938
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 21.at n=43A031519
- Trajectory of 1 under map n->21n+1 if n odd, n->n/2 if n even.at n=14A033967
- Trajectory of 3 under map n->21*n+1 if n odd, n->n/2 if n even.at n=21A037108
- a(n) is smallest number m such that m = n*pi(m), where pi(k) = number of primes <= k (A000720).at n=6A038625
- Numbers k such that pi(k) divides k.at n=29A057809
- Consider the sequence {b(m)} of nonprimes; sequence gives values of m where gcd{m, b(m)} increases.at n=29A058011
- Numbers n divisible by pi(n) [A057809] with prime pi(n); i.e., largest prime factor of n equals pi(n).at n=6A071394
- Consecutive min and max-terms of solution-clusters of A057809, i,e, least and largest solutions to n=x/A000720[x].at n=12A087241
- a(n) = ceiling( 1/2 + (Sum_{i=0..n-1}C(n,i)*C(n,i+1))/2^(n+1) ).at n=15A099779
- Numbers n such that d(n)*pi(n)=n, where d(n) is the number of positive divisors of n.at n=1A104904
- a(n) = 13 + floor(Sum_{j=1..n-1} a(j)/2).at n=16A120140
- a(n) = sqrt(2*(P(n)^4 + 16*P(n+1)^4 + P(n+2)^4)), where P() = Pell numbers A000129.at n=5A133417
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 1), (0, -1, 1), (0, 1, 0), (0, 1, 1), (1, 1, -1)}.at n=7A150517
- Number of lines through at least 2 points of an 8 X n grid of points.at n=24A160848
- Number of binary strings of length n with equal numbers of 00001 and 01011 substrings.at n=14A164200
- Number of 1:3:sqrt(10) proportioned triangles on a (n+1) X (n+1) grid.at n=13A190102
- Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 0,2,1,1,1 for x=0,1,2,3,4.at n=13A197883