9187
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 25
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 9188
- 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
- 9186
- Möbius Function
- -1
- Radical
- 9187
- 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
- 109
- 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
- 1139
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Josephus problem: numbers m such that, when m people are arranged on a circle and numbered 1 through m, the final survivor when we remove every 4th person is one of the first three people.at n=26A005427
- Number of unsensed planar maps with n edges and without faces of degree 1.at n=8A006389
- Numbers k such that the continued fraction for sqrt(k) has period 62.at n=41A020401
- Primes that remain prime through 3 iterations of function f(x) = 10x + 3.at n=27A023300
- 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 95.at n=14A031593
- n! has a palindromic prime number of digits.at n=22A035067
- Primes with first digit 9.at n=36A045715
- Discriminants of imaginary quadratic fields with class number 21 (negated).at n=29A046018
- Primes base 10 that remain primes in six bases b, 2<=b<=10, expansions interpreted as decimal numbers.at n=6A052028
- Number of subsequences of {1..n} such that all differences of pairs of terms are distinct (i.e., number of Golomb rulers on {1..n}).at n=20A054578
- 1 - (5/6)*n + (5/2)*n^2 + (10/3)*n^3 + n^4.at n=9A057675
- Primes p such that p^12 reversed is also prime.at n=24A059705
- Primes with 2 representations: p*q*r - 1 = u*v*w + 1 where p, q, r, u, v and w are primes.at n=28A063644
- a(1) = 1 and a(n) = ceiling((Sum_{k=1..n-1} a(k))/3) for n >= 2.at n=34A072493
- Primes p such that 3p is equidistant from consecutive prime twin pairs.at n=44A074931
- Indices of triple-safe primes: p=prime(n) is double-safe: q=(p-1)/2, r=(q-1)/2 and s=(r-1)/2 are all prime (and q is double-safe).at n=13A075134
- Primes p such that both p-1 and p+1 have at most 3 prime factors, counted with multiplicity; i.e., primes p such that bigomega(p-1) <= 3 and bigomega(p+1) <= 3, where bigomega(n) = A001222(n).at n=34A079153
- Number of square plane partitions of n.at n=31A089299
- a(n) is least prime p such that 7 is the n-th term in the Euclid-Mullin sequence starting at p, or 0 if no such prime p exists.at n=28A094153
- Number of permutations of [n] with exactly 2 valleys which avoid the permutation 1324.at n=7A099745