2820
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
- 24
- Divisor Sum
- 8064
- Proper Divisor Sum (Aliquot Sum)
- 5244
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 736
- Möbius Function
- 0
- Radical
- 1410
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 4
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
- 35
- 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
- yes
- Odd
- no
Appears in sequences
- Certain subgraphs of a directed graph (inverse binomial transform of A005321).at n=5A005327
- Coordination sequence T1 for Zeolite Code AEL.at n=35A008004
- Coordination sequence T1 for Moganite.at n=34A008258
- Expansion of e.g.f. cosh(log(1+x)/exp(x)).at n=6A009139
- a(n) = (n+2)*(n+1)*(n^2 + 7*n - 12)/24.at n=13A014309
- Number of segments created by diagonals of n-gon.at n=12A014629
- From George Gilbert's marks problem: jumping 7 marks at a time (final positions).at n=9A019998
- a(n) = n*(25*n + 1)/2.at n=15A022283
- a(n) = Sum_{i=1..floor((n+1)/4)} a(2*i-1) * a(n-2*i+1), with a(1)=2, a(2)=1, and a(3)=3.at n=10A024741
- Expansion of (theta_3(z)*theta_3(19z) + theta_2(z)*theta_2(19z))^3.at n=43A028643
- Denominators of continued fraction convergents to sqrt(297).at n=9A041559
- Base-9 palindromes that start with 3.at n=18A043030
- Numbers n such that string 7,3 occurs in the base 9 representation of n but not of n-1.at n=38A044317
- Numbers n such that string 2,0 occurs in the base 10 representation of n but not of n-1.at n=31A044352
- Numbers n such that string 8,2 occurs in the base 10 representation of n but not of n-1.at n=30A044414
- Numbers n such that string 7,3 occurs in the base 9 representation of n but not of n+1.at n=38A044698
- Numbers n such that string 2,0 occurs in the base 10 representation of n but not of n+1.at n=31A044733
- Discriminants of imaginary quadratic fields with class number 24 (negated).at n=19A048925
- a(n) = Sum_{i=0..floor(n/2)} T(2i,n-2i) where T is A049627.at n=37A049630
- a(n) = Sum_{i=0..floor(n/2)} T(2i+1,n-2i-1) where T is A049627.at n=37A049631