1605
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 2592
- Proper Divisor Sum (Aliquot Sum)
- 987
- 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
- 848
- Möbius Function
- -1
- Radical
- 1605
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
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
- 21
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Spiral sieve using Fibonacci numbers.at n=15A005624
- Series expansion for rectilinear polymers on square lattice.at n=4A007291
- Number of nonsplit type 2 metacyclic 2-groups of order 2^n.at n=50A007981
- Coordination sequence T1 for Zeolite Code EUO.at n=25A008095
- Coordination sequence for Paracelsian.at n=27A008260
- Coordination sequence T1 for Zeolite Code VET.at n=24A009902
- Number of ferrites M_{10}Y_n that repeat after 6n+50 layers.at n=9A011964
- Number of subsets of {1,...,n} containing an arithmetic progression of length 3.at n=11A018788
- Positive numbers k such that k and 3*k are anagrams in base 9 (written in base 9).at n=15A023080
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = A023532, t = A000201 (lower Wythoff sequence).at n=56A025073
- a(n) = dot_product(1,2,...,n)*(5,6,...,n,1,2,3,4).at n=13A026043
- Numbers having period-14 7-digitized sequences.at n=27A031205
- 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 16.at n=35A031514
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 16.at n=4A031694
- a(n) = floor( (Pi/e)^n ).at n=51A032739
- Coordination sequence T3 for Zeolite Code SBT.at n=32A033614
- Number of partitions satisfying (cn(0,5) = cn(2,5) = cn(3,5) and cn(0,5) <= cn(1,5) and cn(0,5) <= cn(4,5)).at n=44A036821
- Numbers whose base-12 representation has the same nonzero number of 9's and 11's.at n=41A039557
- Numbers k such that 3 and 7 occur juxtaposed in the base-9 representation of k but not of k-1.at n=39A043204
- Numbers k such that 0 and 5 occur juxtaposed in the base-10 representation of k but not of k-1.at n=31A043220