3819
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 5440
- Proper Divisor Sum (Aliquot Sum)
- 1621
- 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
- -1
- Radical
- 3819
- 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
- 30
- 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
- Coordination sequence T4 for Zeolite Code MEI.at n=45A008149
- a(n) = (d(n) - r(n))/5, where d = A026037 and r is the periodic sequence with fundamental period (1,2,0,2,0).at n=36A026039
- 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 19.at n=27A031517
- a(n)=(s(n)+4)/9, where s(n)=n-th base 9 palindrome that starts with 5.at n=39A043076
- Numbers whose base-4 representation contains exactly three 2's and three 3's.at n=13A045151
- Numbers n such that 241*2^n-1 is prime.at n=8A050879
- Number of points in N^6 of norm <= n.at n=5A055405
- Number of points in N^n of norm <= 5.at n=6A055420
- Composites for which the row of the prime-composite array (A063173) includes the leftmost element of both a zero-only antidiagonal and a zero-only diagonal(A067681).at n=30A063176
- Rounded total surface area of a regular icosahedron with edge length n.at n=21A071398
- Gives an LCD representation of n.at n=24A071843
- a(n) = Sum_{k=1..n} -mu(k+1) * a(n-k), with a(0)=1.at n=16A073776
- Leading term of n-th row of A081491.at n=23A081490
- Smallest nontrivial multiple of n ending in n. By nontrivial one means a(n) is not equal to n or concatenation of n with itself.at n=18A083466
- First occurrence of n in A093723, or -1 if n does not occur.at n=46A093724
- If p(x) is the x-th prime, then the n-th set of 3 consecutive sexy prime pairs starts at p(a(n)).at n=38A095962
- Conjectured numbers n such that the trajectory of n as defined in A003508 is unique.at n=13A105233
- Shorthand of n-th smallest n-digit prime, see comments.at n=44A107108
- a(1) = 11, a(n) = least k such that concatenation of n copies of k with all previous concatenation gives a prime.at n=40A111477
- Least multiple of prime(n) ending in digits of n.at n=15A114012