3021
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 6
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 4320
- Proper Divisor Sum (Aliquot Sum)
- 1299
- 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
- 1872
- Möbius Function
- -1
- Radical
- 3021
- 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
- 66
- 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
- a(n) = ceiling(Pi^n).at n=7A001673
- a(n) = (4*n+1)*(4*n+5).at n=13A003185
- a(n) = a(n-1) + a(n-9) for n >= 9; a(n) = 1 for n=0..7; a(8) = 2.at n=45A005711
- Least k such that binomial(k,n) has n or more distinct prime factors.at n=45A005733
- Coordination sequence T2 for Zeolite Code BRE.at n=36A008059
- Coordination sequence T2 for Zeolite Code EUO.at n=34A008097
- Coordination sequence T4 for Zeolite Code EUO.at n=34A008099
- Coordination sequence T4 for Zeolite Code MFI.at n=35A008167
- Coordination sequence T8 for Zeolite Code MFI.at n=35A008171
- Expansion of 1/(1 - x^9 - x^10 - ...).at n=55A017903
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite MEI = ZSM-18 Nan[AlnSi34-nO68].28H2O (n=2.1-5.7) starting with a T1 atom.at n=11A019145
- a(1) = 2; a(n+1) = a(n)-th composite.at n=24A022450
- Numbers k such that Fibonacci(k) == 2 (mod k).at n=47A023174
- a(n) = [ 2nd elementary symmetric function of {sqrt(k+1)} ], k = 1,2,...,n.at n=21A025219
- Index of 10^n within the sequence of the numbers of the form 2^i*10^j.at n=42A025740
- Triangle T by rows: second differences of Motzkin triangle (A026300), (i >= -1, -1<=j<=i).at n=73A026120
- a(n) = number of (s(0),s(1),...,s(n)) such that every s(i) is a nonnegative integer, s(0) = 1, s(n) = 4, |s(1) - s(0)| = 1, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-3), where T is the array in A026120.at n=7A026125
- Positions of records in A030757.at n=47A030762
- Exactly 5 digits from {1,2,3,4,5,6,7,8,9} can precede a(n) to form a lucky number.at n=15A032701
- Number of partitions satisfying (cn(0,5) <= cn(1,5) = cn(4,5) and cn(1,5) <= cn(2,5) and cn(1,5) <= cn(3,5)).at n=45A036819