9981
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
- 6
- Divisor Sum
- 14430
- Proper Divisor Sum (Aliquot Sum)
- 4449
- 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
- 6648
- Möbius Function
- 0
- Radical
- 3327
- Omega Function (Ω)
- 3
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 73
- 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
- a(n) = floor(n*phi^12), where phi is the golden ratio, A001622.at n=31A004927
- Expansion of free energy series related to Potts model.at n=4A007276
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 44 ones.at n=39A031812
- T(2n+1,n), array T as in A054134.at n=5A054140
- Least m such that P + m is a prime, where P is the n-th perfect number.at n=18A078096
- a(n) is the smallest nonprime k such that tau(k + n) = tau(k) + n , where tau(n) is the number of divisors of n (A000005).at n=18A099642
- Berend Jan van der Zwaag's conjectured complete list of numbers that start different "expanding periodic loops" under the mapping described in A053392 and A060630.at n=14A103117
- Composite numbers between largest n-digit prime and the smallest (n+1) digit prime.at n=24A109936
- Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n having k ascents of length 2 starting at an odd level (0<=k<=floor(n/2)-1 for n>=2; k=0 for n=0,1).at n=22A114463
- Number of Dyck paths of semilength n having no ascents of length 2 that start at an odd level.at n=10A114465
- a(n) = the largest n-digit number with exactly 6 divisors, a(n) = 0 if no such number exists.at n=3A182672
- a(n) = the largest 4-digit number with exactly n divisors, a(n) = 0 if no such number exists.at n=5A182696
- Number of length 3 1..(n+2) arrays with no leading or trailing partial sum equal to a prime and no consecutive values equal.at n=34A254220
- Number of odd singletons in all partitions of n (n>=0).at n=32A265257
- Numbers n such that n+2, n+4, n+6, n+8, n+10, n+12 and n+14 are all semiprimes.at n=3A268578
- G.f. is the cube of the g.f. of A006950.at n=16A273226
- Numbers whose digit string can be partitioned into three nonempty parts a <= b <= c such that a*b = c.at n=44A280732
- Odd numbers for which sigma(k) is congruent to 2 modulo 4 and the 3-adic valuation of k is one larger than the 3-adic valuation of sigma(k).at n=36A351534
- Table read by antidiagonals: Place k points in general position on each side of a regular n-gon and join every pair of the n*(k+1) boundary points by a chord; T(n,k) (n >= 3, k >= 0) gives number of vertices in the resulting planar graph.at n=33A367183
- Numbers without comma-successors: these are the numbers k such that if the commas sequence A121805 is started at k instead of 1, there is no second term.at n=23A367341