9109
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
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 9110
- 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
- 9108
- Möbius Function
- -1
- Radical
- 9109
- 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
- 60
- 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
- 1130
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Maximal number of regions obtained by joining n points around a circle by straight lines. Also number of regions in 4-space formed by n-1 hyperplanes.at n=22A000127
- Place n equally-spaced points around a circle and join every pair of points by a chord; this divides the circle into a(n) regions.at n=22A006533
- Numbers k such that the continued fraction for sqrt(k) has period 69.at n=10A020408
- Primes that remain prime through 3 iterations of function f(x) = 2x + 5.at n=28A023274
- Primes that remain prime through 3 iterations of function f(x) = 3x + 10.at n=43A023280
- Primes that remain prime through 4 iterations of function f(x) = 2x + 5.at n=13A023304
- Numbers with exactly 7 1's in their ternary expansion.at n=34A023698
- a(n) = A027113(n, 2n-6).at n=8A027124
- Lower prime of a difference of 18 between consecutive primes.at n=36A031936
- Sums of 7 distinct powers of 3.at n=19A038469
- Sums of 4 distinct powers of 6.at n=10A038480
- Primes with first digit 9.at n=27A045715
- First member of a prime triple in a 2p-1 progression.at n=40A057326
- Prime having only {0, 1, 4, 9} as digits.at n=44A061246
- Primes with 10 as smallest positive primitive root.at n=23A061323
- Primes starting and ending with 9.at n=5A062335
- The first of two consecutive primes with equal digital sums.at n=23A066540
- Primes formed from the concatenation of k, k+1 and k for some k.at n=1A068660
- Prefixing, suffixing or inserting a 9 in the number anywhere gives a prime.at n=37A069833
- a(1) = 2, a(n+1) is smallest prime factor of (2 * Product_{k=1..n} a(k)) + 1.at n=31A077073