9871
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
- 9872
- 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
- 9870
- Möbius Function
- -1
- Radical
- 9871
- 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
- 197
- 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
- 1218
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Largest prime with n distinct decimal digits.at n=3A007810
- Primes that remain prime through 3 iterations of function f(x) = 2x + 9.at n=24A023276
- Primes that remain prime through 4 iterations of function f(x) = 2x + 9.at n=9A023306
- n written in fractional base 10/9.at n=31A024664
- Largest n-digit norep emirp.at n=3A030540
- 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=6A031597
- Multiplicity of highest weight (or singular) vectors associated with character chi_115 of Monster module.at n=41A034503
- Primes of form 210*p + 1 where p is a prime.at n=9A051648
- Primes p such that p-12, p and p+12 are consecutive primes.at n=5A053072
- Primes of the form k(k+1)/2+1 (i.e., central polygonal numbers, or one more than triangular numbers).at n=38A055469
- Primes p such that x^47 = 2 has no solution mod p.at n=27A059257
- a(n) = 6*n^2 + 6*n + 31.at n=40A060834
- Primes of the form 6*k^2 + 6*k + 31.at n=35A060844
- Numbers k such that A048138(k) is a prime and sets a new record for such primes.at n=31A064440
- Emirps which when concatenated with their reversals after a 0 make a palindromic prime of the form emirp0prime.at n=39A070954
- Largest n-digit prime with strictly decreasing digits.at n=3A071361
- Primes of the form 210n + 1.at n=22A073102
- Smallest squarefree integer k such that Q(sqrt(k)) has class number n.at n=14A081363
- Numbers p such that p = (prime(n)+ prime(n+2))/2 is prime for prime indices n=2, 3, 5...at n=14A098038
- Smallest and largest primes pairwise displayed with k digits from k=1,...,9 with distinct decimal digits.at n=7A099629