9181
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
- 9182
- 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
- 9180
- Möbius Function
- -1
- Radical
- 9181
- 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
- 1138
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Sextan primes: p = (x^6 + y^6)/(x^2 + y^2).at n=18A002647
- Numbers k such that the continued fraction for sqrt(k) has period 37.at n=19A020376
- Primes that remain prime through 3 iterations of function f(x) = 2x + 5.at n=29A023274
- a(n) = A027113(n, 2n-2).at n=8A027120
- Greatest number in row n of array T given by A027113.at n=10A027133
- Primes that are palindromic in base 9.at n=21A029977
- Primes p such that (p+1)/2 and (p+2)/3 are also primes.at n=23A036570
- a(n) = (9*n^2 + 3*n + 2)/2.at n=45A038764
- Numerators of continued fraction convergents to sqrt(458).at n=4A041872
- Primes with first digit 9.at n=35A045715
- Primes whose consecutive digits differ by 7 or 8.at n=12A048419
- Primes of the form k(k+1)/2+1 (i.e., central polygonal numbers, or one more than triangular numbers).at n=37A055469
- a(n) is the greatest prime factor of a(n-1)^2+a(n-1)+1.at n=6A056650
- Primes p such that p^12 reversed is also prime.at n=23A059705
- Take A000040, omit commas: 23571113171923..., select 4-digit primes seen when scanning from left.at n=16A073037
- Numbers k such that 1/(1/phi(k) + 1/phi(k+1) + 1/phi(k+2)) is an integer.at n=41A073543
- Concatenate the primes as 2357111317192329313..., then insert commas from left to right so that between each pair of successive commas is a prime, always making the new prime as small as possible.at n=27A074721
- Smallest prime of the form concatenation n, 2n, 3n,...kn and 1.at n=8A090921
- Number of 4 X 4 symmetric magic squares with line sum 2n.at n=10A093198
- Fundamental discriminants of real quadratic number fields with class number 5.at n=42A094614