9811
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
- 2
- Divisor Sum
- 9812
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 9810
- Möbius Function
- -1
- Radical
- 9811
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 166
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1210
- 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 even period and if the last term of the periodic part is deleted the central term is 99.at n=1A031597
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 86 ones.at n=4A031854
- Multiplicity of highest weight (or singular) vectors associated with character chi_7 of Monster module.at n=44A034395
- Base 8 digits are, in order, the first n terms of the periodic sequence with initial period 2,3,1.at n=4A037643
- Sums of 7 distinct powers of 3.at n=31A038469
- Discriminants of imaginary quadratic fields with class number 21 (negated).at n=30A046018
- Primes of the form 2*n^2 + 11.at n=37A050265
- Numbers k such that 80*R_k + 9 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=6A056663
- a(n) is the least prime p, such that next_prime(2*p) - 2*p = 2*n - 1.at n=19A059846
- Average of terms of n-th row of A077321.at n=41A077325
- Number of distinct lines through the origin in 3-dimensional cube of side length n.at n=22A090025
- a(n) = (15*n^2 + 5*n + 2)/2.at n=35A093500
- List of primes produced by a certain "prime-generating" quartic polynomial.at n=30A096372
- Primes from merging of 4 successive digits in decimal expansion of Catalan's constant.at n=11A104918
- Numbers n such that concatenation of n and its 10's complement is a palindrome.at n=10A109625
- Start with 1 and repeatedly reverse the digits and add 55 to get the next term.at n=18A118161
- Area of the spiral of equilateral triangles with side lengths which follow the Padovan sequence, divided by the area of the initial triangle.at n=16A133044
- Primes of the form k^2 + 10.at n=18A138355
- Primes of the form 4x^2+4xy+211y^2.at n=36A139985
- Primes of the form 43x^2+2xy+43y^2.at n=36A140041