9005
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 10812
- Proper Divisor Sum (Aliquot Sum)
- 1807
- 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
- 7200
- Möbius Function
- 1
- Radical
- 9005
- 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
- 39
- 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 that are the sum of 7 positive 7th powers.at n=28A003374
- a(n) = s(1)*s(n) + s(2)*s(n-1) + ... + s(k)*s(n+1-k), where k = floor((n+1)/2), s = (odd natural numbers).at n=29A024598
- a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n-k+1), where k = floor(n/2), s = (odd natural numbers).at n=28A025112
- Number of partitions of n into an even number of parts.at n=36A027187
- Positive numbers having the same set of digits in base 7 and base 9.at n=39A037439
- Number of cycle types of conjugacy classes of all even permutations of n elements.at n=36A046682
- Numbers n such that 225*2^n-1 is prime.at n=13A050864
- Let Py(n)=A000330(n)=n-th square pyramidal number. Consider all integer triples (i,j,k), j >= k>0, with Py(i)=Py(j)+Py(k), ordered by increasing i; sequence gives j values.at n=40A053720
- a(n) = Sum_{i=n+1..2n} prime(i) - Sum_{i=1..n} prime(i).at n=40A077354
- a(n) = (A085249(n) - 1)/6.at n=18A088349
- Records in A007535.at n=27A098654
- Number of irregular primes less than 2^n.at n=17A105456
- Number of permutations in S_n avoiding {bar 2}413{bar 5} (i.e., every occurrence of 413 is contained in an occurrence of a 24135).at n=9A137551
- Triangle T(n, k) = ( k*(n-k+1) )^3 - 2^(n-1), read by rows.at n=38A141388
- Triangle T(n, k) = ( k*(n-k+1) )^3 - 2^(n-1), read by rows.at n=42A141388
- a(n) = n*(8*n^2 + 1)/3.at n=15A143166
- Number of ways to place zero or more nonadjacent 2,0 3,1 4,2 4,3 4,4 5,2 6,2 polyhexes in any orientation on a planar nXnXn triangular grid.at n=9A155354
- Duplicate of A137551.at n=8A160701
- Smallest sequence which lists the position of digits "8" in the sequence.at n=38A167450
- a(n) = n*(n+1)*(2*n+1)/6 - n*floor(n/2).at n=29A178946