8991
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 13832
- Proper Divisor Sum (Aliquot Sum)
- 4841
- 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
- 5832
- Möbius Function
- 0
- Radical
- 111
- Omega Function (Ω)
- 6
- Little Omega Function (ω)
- 2
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 140
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Number of partitions of n in which no parts are multiples of 3.at n=43A000726
- Numbers k that divide s(k), where s(1)=1, s(j)=7*s(j-1)+j.at n=40A014854
- Numbers k such that k divides s(k), where s(1)=1, s(j)= s(j-1) + j*7^(j-1).at n=22A014948
- Numbers m such that m divides 10^m - 1.at n=14A014950
- Numbers k such that k | 11^k + 1.at n=17A015960
- Number of partitions of n into parts 3k and 3k+1 with at least one part of each type.at n=47A035618
- Odd numbers divisible by exactly 6 primes (counted with multiplicity).at n=26A046319
- Iterated procedure 'composite k added to sum of its prime factors reaches a prime' yields 7 skipped primes.at n=45A050774
- a(n) = T(n,n-4), array T as in A055807.at n=33A055809
- Lesser of the smallest pair of consecutive numbers divisible by an n-th power, but neither divisible by an (n+1)-st power.at n=4A059737
- Numbers k such that sigma(k) - phi(k) is a cube.at n=35A062385
- Numbers k such that sopf(k) = sopf(k+2), where sopf(k) = A008472(k).at n=9A063968
- Partial sums of sequence (essentially A002378): 1, 2, 6, 12, 20, 30, 42, 56, 72, 90, ...at n=29A064999
- Lesser of two consecutive numbers each divisible by a fourth power.at n=16A068782
- Lesser of two consecutive numbers each divisible by a fifth power.at n=2A068783
- Smaller of two consecutive numbers with the same prime signature not occurring earlier.at n=10A085929
- a(n) = 9*(10^n - 1).at n=3A086580
- Smaller of two consecutive numbers with the same prime signature not occurring earlier.at n=11A091405
- Numbers whose square is the concatenation of two numbers k and k-2.at n=2A115442
- Numbers k such that k and k^2 use only the digits 0, 1, 3, 8 and 9.at n=30A136852