4221
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 7072
- Proper Divisor Sum (Aliquot Sum)
- 2851
- 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
- 2376
- Möbius Function
- 0
- Radical
- 1407
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 170
- 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
- Related to series-parallel networks.at n=7A006349
- Number of connected vertex-transitive graphs with n nodes.at n=25A006800
- Coordination sequence T3 for Zeolite Code MOR.at n=42A008184
- Pisot sequence E(8,10), a(n) = floor( a(n-1)^2/a(n-2) + 1/2 ).at n=25A010916
- Number of triples of different integers from [ 2,n ] with no global factor.at n=31A015618
- Convolution of natural numbers with (1, p(1), p(2), ... ), where p(k) is the k-th prime.at n=20A023538
- Strings giving winning positions in Tchoukaillon (or Mancala) solitaire.at n=9A028931
- Expansion of Product_{m>=1} ((1+q^(2*m-1))/(1+q^(2*m)))^7.at n=17A029844
- Numbers in which all pairs of consecutive base-6 digits differ by 2.at n=44A033084
- Number of partitions of n with equal nonzero number of parts congruent to each of 0, 1 and 4 (mod 5).at n=52A035584
- Number of partitions satisfying (cn(0,5) = 0 and cn(1,5) = cn(4,5)).at n=46A036818
- Positive numbers having the same set of digits in base 8 and base 9.at n=22A037441
- Base 6 digits are, in order, the first n terms of the periodic sequence with initial period 3,1.at n=4A037585
- Denominators of continued fraction convergents to sqrt(858).at n=5A042657
- Base-6 palindromes that start with 3.at n=23A043012
- Coordination sequence T2 for Zeolite Code MSO.at n=45A047964
- a(n) is smallest number such that number of primes produced according to rules stipulated in Honaker's A048853 is n.at n=15A050662
- a(n) = a(n-1) + n^2 if n prime else a(n-1) - n, starting with a(0) = 0.at n=37A051353
- 22-gonal numbers: a(n) = n*(10*n-9).at n=21A051874
- Numbers with more than one factorization into S-primes. See A054520 and A057948 for definition.at n=21A057949