3639
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
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 4856
- Proper Divisor Sum (Aliquot Sum)
- 1217
- 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
- 2424
- Möbius Function
- 1
- Radical
- 3639
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 162
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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 T3 for Zeolite Code DFO.at n=46A009877
- Partial sums of primes, if 1 is regarded as a prime (as it was until quite recently, see A008578).at n=43A014284
- Coordination sequence T1 for Zeolite Code CZP.at n=39A019456
- Fibonacci sequence beginning 1, 15.at n=13A022105
- a(n) = [ Sum{(log(j)-log(i))^3} ], 2 <= i < j <= n.at n=53A025207
- 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 40.at n=14A031538
- Concatenation of n and n + 3.at n=35A032608
- Number of partitions of n with equal nonzero number of parts congruent to each of 2 and 4 (mod 5).at n=39A035570
- Squarefree nonprimes with property that the concatenation of the prime factors is a palindrome.at n=34A046448
- Semiprimes whose prime factors, when concatenated, yield a palindrome.at n=32A046451
- Nonprime numbers n such that n and n-reversed (<>n and no leading zeros) have the same number of prime factors and these prime factors (palindromes allowed here) are also reversals of each other.at n=43A050702
- When squared gives number composed just of the digits 1, 2, 3, 4.at n=21A061677
- C(n+3)=2*C(n), where C(n) is Cototient(n) := n - phi(n) (A051953).at n=25A063480
- Numbers that in base 2 need twelve 'Reverse and Add' steps to reach a palindrome.at n=19A066133
- Integers n such that the 'Reverse and Add!' trajectory of n joins the trajectory of 111.at n=41A070798
- Numbers k such that phi(k*sigma(k)) = phi(k)^2.at n=39A082954
- a(1) = 4 and then least composite such that every partial concatenation of 2 or more terms is a prime.at n=31A086474
- a(n) = n*F(n-1) + F(n), where F = A000045.at n=14A094588
- Iccanobirt prime indices (15 of 15): Indices of prime numbers in A102125.at n=18A102145
- a(n)=the sum of the (1,2)- and (1,3)-entries and twice the (1,4)-entry of the matrix P^n + T^n, where the 4 X 4 matrices P and T are defined by P=[0,1,0,0;0,0,1,0;0,0,0,1;1,0,0,0] and T=[0,1,0,0;0,0,1,0;0,0,0,1;1,0,0,1].at n=27A109526