11989
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 28
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 12640
- Proper Divisor Sum (Aliquot Sum)
- 651
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11340
- Möbius Function
- 1
- Radical
- 11989
- 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
- 50
- 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
- Strong pseudoprimes to base 43.at n=13A020269
- Least m such that if r and s in {1/1, 1/3, 1/6,..., 1/C(n+1,2)} satisfy r < s, then r < k/m < s for some integer k.at n=39A024826
- a(n) = Sum_{ d|n } sigma(n/d)*d^4.at n=9A027848
- Number of perfect matchings in graph C_{9} X P_{2n}.at n=2A028480
- [ exp(13/15)*n! ].at n=6A030909
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 60 ones.at n=29A031828
- Denominators of continued fraction convergents to sqrt(84).at n=4A041149
- Denominators of continued fraction convergents to sqrt(336).at n=4A041635
- Denominators of continued fraction convergents to sqrt(756).at n=4A042457
- Numbers n such that 49*2^n-1 is prime.at n=21A050550
- 19-gonal (or enneadecagonal) numbers: n(17n-15)/2.at n=38A051871
- Truncated triangular pyramid numbers: a(n) = Sum_{k=4..n} (k*(k+1)/2 - 9).at n=37A051937
- At stage 1, start with a unit equilateral equiangular triangle. At each successive stage add 3*(n-1) new triangles around outside with edge-to-edge contacts. Sequence gives number of triangles (regardless of size) at n-th stage.at n=29A064412
- Centered 18-gonal numbers.at n=36A069131
- Least k such that 10^(2n-1)+k is a brilliant number.at n=43A084476
- Multiples of 19 containing a 19 in their decimal representation.at n=23A121039
- Numbers k arising in A144929.at n=2A144930
- a(n) = 324*n + 1.at n=36A158272
- Numbers k such that 6*prime(k) -+ {1,5} are all prime.at n=20A174393
- The sums of pairs of adjacent terms are the odd palindromic primes in ascending order.at n=36A181884