4905
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 8580
- Proper Divisor Sum (Aliquot Sum)
- 3675
- 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
- 2592
- Möbius Function
- 0
- Radical
- 1635
- Omega Function (Ω)
- 4
- 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
- 165
- 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 3-covers of an unlabeled n-set.at n=13A005783
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 28.at n=4A031706
- a(n)=number of Gaussian integers z=a+bi satisfying |z|<=n+1/2.at n=39A036704
- Coordination sequence T8 for Zeolite Code SFF.at n=46A038435
- Gaps of 7 in sequence A038593 (lower terms).at n=19A038653
- Numbers that are divisible by 5 and are the difference between two (different positive) cubes in at least one way.at n=23A038853
- Numbers ending with '5' that are the difference of two positive cubes.at n=16A038860
- Numbers n such that 55*2^n-1 is prime.at n=29A050553
- Number of 4 X n binary matrices such that any 2 rows have a common 1, up to column permutations.at n=5A052388
- Number of positive integers <= 2^n of form x^2 + 8 y^2.at n=15A054152
- Seventh column of quintinomial coefficients.at n=8A064056
- a(n) = sum of modular offsets: mod[n+c,b]-(mod[n,b]+c) for c<=b<=n.at n=34A066809
- Numbers k such that sigma_k(k)/k is an integer, where sigma_k(k) is the sum of the k-th powers of the divisors of k (A023887).at n=34A067313
- a(1) = 1, a(n) = a(n-1) + phi(a(n-1)).at n=16A074693
- Natural numbers of the form p^3 - q^3, where p and q are primes.at n=22A086120
- Positive sums or differences of two cubes of primes.at n=43A086121
- Sum of all numbers with n digits.at n=1A101291
- The values of a in a^2 + b^2 = c^2 where b - a = 23 and gcd(a,b,c)=1.at n=6A117476
- Nonnegative values x of solutions (x, y) to the Diophantine equation x^2 + (x + 23)^2 = y^2.at n=10A118337
- Let A(0) = 1, B(0) = 0; A(n+1) = Sum_{k=0..n} binomial(n,k)*B(k), B(n+1) = Sum_{k=0..n} -binomial(n,k)*A(k); entry gives A sequence (cf. A121868).at n=9A121867