9939
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 30
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 13256
- Proper Divisor Sum (Aliquot Sum)
- 3317
- 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
- 6624
- Möbius Function
- 1
- Radical
- 9939
- Omega Function (Ω)
- 2
- 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
- yes
- Squarefree Number
- yes
- 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
- 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 33.at n=29A031531
- a(n) = ceiling((n + 1/2)^3).at n=20A034131
- Numbers having three 9's in base 10.at n=21A043527
- Harmonic mean of digits is 6.at n=21A062184
- Cycle of the inventory sequence (as in A063850) starting with n consists of prime numbers.at n=33A078970
- a(1)=1, a(n) = -1 + n*Sum_{j=1..n-1} a(j).at n=6A082425
- Numbers k such that 10^k + 5*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=18A102938
- Near-repdigit semiprimes with 9 as repeated digit.at n=19A105990
- a(n) = A000043(n)-2.at n=21A153798
- Floor-Sqrt transform of numbers of A078678 (Grand Dyck paths with no zigzags).at n=21A192682
- Constant term of the reduction by x^2 -> x+1 of the polynomial p(n,x) defined at Comments.at n=16A192969
- Expansion of (-x^2 + 3*x - 1)/(x^3 - x^2 + 3*x - 1).at n=12A200752
- Number of partitions of n+6 with largest inscribed rectangle having area <= n.at n=27A218627
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 189", based on the 5-celled von Neumann neighborhood.at n=23A270679
- Positions of 3's in A264977; positions of 6's in A277330.at n=28A277713
- Numbers with digits 3 and 9 only.at n=27A284964
- Numbers in which 9 outnumbers all other digits together.at n=49A292739
- Number of equivalence classes of binary words of length n for the set of subwords {010, 101}.at n=16A317783
- Number of times the digit 6 appears in the first 10^n decimal digits of sqrt(2), sometimes called Pythagoras's constant, counting after the decimal point.at n=4A322647
- a(n) = number of partitions of n whose difference multiset has at least one duplicate; see Comments.at n=33A364612