4821
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 6432
- Proper Divisor Sum (Aliquot Sum)
- 1611
- 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
- 3212
- Möbius Function
- 1
- Radical
- 4821
- 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
- 20
- 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
- a(n) = (n+1)*a(n-1) + (n+2)*a(n-2) + a(n-3); a(1)=0, a(2)=3, a(3)=13.at n=5A000904
- Oscillates under partition transform.at n=40A007211
- Coordination sequence T1 for Zeolite Code MEP.at n=41A008157
- Expansion of 1/(1 - x^4 - x^5 - x^6 - x^7).at n=39A017829
- Sum{T(n-k,k)}, 0<=k<=[ n/2 ], T given by A026659.at n=17A026669
- 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 46.at n=19A031544
- Number of primes < n^3.at n=35A038098
- Numbers whose base-2 representation has exactly 11 runs.at n=20A043578
- a(n) = (1/2)*(n-th number whose base-2 representation has exactly 12 runs).at n=22A043686
- Numbers n such that number of runs in the base 2 representation of n is congruent to 1 mod 10.at n=32A043764
- a(1) = 4; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=37A046254
- Discriminants of real quadratic fields with class number 1 and related continued fraction period length of 20.at n=15A050969
- Number of primes < 6^n.at n=6A055731
- Number of primes < n^n.at n=5A064151
- a(n) = floor(e^n mod n^e).at n=31A066433
- Radii n of circles with integer radius that can approximately be squared integrally: the floor or ceiling of Pi*n^2 is an integer square.at n=4A067561
- Numbers k such that average of prime(k) and prime(k+1) is a perfect square.at n=30A076692
- Numbers n such that the average of prime(n) and prime(n+1) is a perfect cube.at n=5A076693
- a(1)=4, then least semiprime > a(n-1) such that when all in the sequence are concatenated together they form a prime.at n=22A085703
- Number of permutations of length n which avoid the patterns 321, 1324, 2341.at n=45A116733