9989
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 35
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 11424
- Proper Divisor Sum (Aliquot Sum)
- 1435
- 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
- 8556
- Möbius Function
- 1
- Radical
- 9989
- 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
- 91
- 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
- Numbers k such that the continued fraction for sqrt(k) has period 80.at n=32A020419
- Numbers having three 9's in base 10.at n=26A043527
- a(n) = smallest multiple of 7 with a digit sum = n.at n=33A077493
- Numbers k such that k, k+2, k+4, k+6, k+8 are semiprimes.at n=32A092127
- Near-repdigit semiprimes with 9 as repeated digit.at n=23A105990
- Composite numbers between largest n-digit prime and the smallest (n+1) digit prime.at n=32A109936
- Start with 1015 and repeatedly reverse the digits and add 4 to get the next term.at n=43A117807
- Start with 1027 and repeatedly reverse the digits and add 16 to get the next term.at n=55A119455
- a(n) = n^4 - n - 1.at n=9A126423
- Numbers k such that 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)*p(k+5)-1 and 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)*p(k+5)+1 are twin primes with p(h) = h-th prime.at n=16A129311
- a(n+1) = A154771(a(n)) = sum of all distinct "valid substrings" of a(n); a(1)=10 (least nontrivial choice).at n=35A154770
- Number of binary strings of length n with equal numbers of 00101 and 10110 substrings.at n=14A164250
- Partial sums of A053519.at n=6A174458
- Numbers with rounded up arithmetic mean of digits = 9.at n=44A178369
- Increasing sequence generated by these rules: a(1)=1, and if x is in a then 3x+2 and 4x-3 are in a.at n=55A191139
- Number of (3+2) X (n+2) 0..4 arrays with every consecutive three elements in every row and diagonal having exactly two distinct values, and in every column and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=10A252964
- Number of (n+2)X(2+2) 0..1 arrays with no 3x3 subblock diagonal sum 1 and no antidiagonal sum 2 and no row sum 0 and no column sum 0.at n=5A255085
- Number of (n+2)X(6+2) 0..1 arrays with no 3x3 subblock diagonal sum 1 and no antidiagonal sum 2 and no row sum 0 and no column sum 0.at n=1A255089
- T(n,k)=Number of (n+2)X(k+2) 0..1 arrays with no 3x3 subblock diagonal sum 1 and no antidiagonal sum 2 and no row sum 0 and no column sum 0.at n=22A255091
- T(n,k)=Number of (n+2)X(k+2) 0..1 arrays with no 3x3 subblock diagonal sum 1 and no antidiagonal sum 2 and no row sum 0 and no column sum 0.at n=26A255091