12820
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 26964
- Proper Divisor Sum (Aliquot Sum)
- 14144
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5120
- Möbius Function
- 0
- Radical
- 6410
- 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
- 63
- 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
- Consider the trajectory of n under the iteration of a map which sends x to 3x - sigma(x) if this is >= 0; otherwise the iteration stops. The sequence gives values of n which eventually reach 0.at n=25A037159
- Integers expressible as the sum of (at least two) consecutive primes in at least 4 ways.at n=26A067374
- Let f(x)=(largest digit of x)^(smallest digit of x) + x (A097385). Sequence gives numbers n such that f(n) and f(n+1) are both prime.at n=30A097387
- Where A007535 reaches a record.at n=32A098653
- Least number having n orderless representations as p^2 + q^2 + r^2 + s^2, where p, q, r, and s are primes.at n=43A214513
- Number of nondecreasing -4..4 vectors of length n whose dot product with some nondecreasing -4..4 vector equals n.at n=7A226407
- Partial sums of A243980.at n=21A244050
- Numbers such that the largest prime factor equals the sum of the 4th power of the other prime factors.at n=11A244344
- Number of tilings of a 5 X n rectangle using n pentominoes of shapes L, U, X.at n=13A247125
- Number of length n+2 0..3 arrays with the sum of second differences squared multiplied by some arrangement of +-1 equal to zero.at n=5A250315
- T(n,k)=Number of length n+2 0..k arrays with the sum of second differences squared multiplied by some arrangement of +-1 equal to zero.at n=33A250320
- Number of length 6+2 0..n arrays with the sum of second differences squared multiplied by some arrangement of +-1 equal to zero.at n=2A250325
- a(n) = k is a number such that A007535(k), the smallest pseudoprime to base k ( > k), is the n-th Carmichael number.at n=8A293563
- a(n) = Sum_{k=1..n} (-1)^(k-1) * binomial(floor(n/k)+2,3).at n=42A366395
- Expansion of g.f. A(x) satisfying A(x) = 1 + 3*x*A(x)^2 - 2*x*A(-x)^2.at n=6A368635
- Integers k such that 2^k contains all powers of 2 not exceeding k as substrings.at n=44A372680