8989
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 34
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9180
- Proper Divisor Sum (Aliquot Sum)
- 191
- 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
- 8800
- Möbius Function
- 1
- Radical
- 8989
- Omega Function (Ω)
- 2
- 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
- 78
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- no
- Odd
- yes
Appears in sequences
- Crystal ball sequence for 6-dimensional cubic lattice.at n=6A001848
- Central Delannoy numbers: a(n) = Sum_{k=0..n} C(n,k)*C(n+k,k).at n=6A001850
- Numbers k such that the continued fraction for sqrt(k) has period 77.at n=8A020416
- a(n) = T([n/2],[(n+1)/2]), where T = Delannoy triangle (A008288).at n=12A026003
- Lucky numbers that are concatenations of a number k with itself.at n=10A032650
- Exactly 5 digits from {1,2,3,4,5,6,7,8,9} can precede a(n) to form a lucky number.at n=32A032701
- a(n)^2 is a square whose digits occur with an equal minimum frequency of 2.at n=39A052049
- Convolution of A055852 with A011782.at n=7A055853
- Integers n > 1997 such that the 'Reverse and Add!' trajectory of n joins the trajectory of 1997.at n=15A063055
- Largest n-digit number in which the k-th digit is a divisor or a multiple of k.at n=3A069573
- Octo numbers (a polygonal sequence): a(n) = 5*n^2 - 6*n + 2 = (n-1)^2 + (2*n-1)^2.at n=42A079273
- a(n) = prime(n)*prime(n+2).at n=23A090076
- Number of nonisomorphic partitions of n on the Ferrers diagram.at n=36A095814
- Triangle, read by rows, of trinomial coefficients arranged so that there are n+1 terms in row n by setting T(n,k) equal to the coefficient of z^k in (2 + 3*z + z^2)^(n-[k/2]), for n>=k>=0, where [k/2] is the integer floor of k/2.at n=51A099527
- A symmetric number triangle based on 2^n.at n=24A108477
- a(n) = A007290(n+2) - 1 = 2*C(n+2,3) - 1.at n=29A108766
- Number triangle, equal to half of Delannoy square array A008288.at n=21A113139
- Riordan array (1/(1-x), x*(1+x)^2/(1-x)^2).at n=48A114123
- n times n+4 gives the concatenation of two numbers m and m-6.at n=1A116248
- a(1)=1, a(2)=3, a(3)=8; for n>=4, a(n) = 10*a(n-3) + 8 (if a(n-3) is odd) or + 9 (if a(n-3) is even).at n=11A117713