2781
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 4160
- Proper Divisor Sum (Aliquot Sum)
- 1379
- 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
- 1836
- Möbius Function
- 0
- Radical
- 309
- Omega Function (Ω)
- 4
- 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
- 128
- 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
- no
- Odd
- yes
Appears in sequences
- Number of Twopins positions.at n=17A005685
- Number of non-Abelian metacyclic groups of order 2^n.at n=46A007982
- Coordination sequence T2 for Zeolite Code ZON.at n=37A009920
- a(n) is the concatenation of n and 3n.at n=26A019551
- a(n) = Sum_{k=0..n} (n-k+1)^k.at n=8A026898
- Lucky numbers with size of gaps equal to 8 (upper terms).at n=31A031891
- a(n) = n * prime(n).at n=26A033286
- Number of partitions of n into parts 3k or 3k+1.at n=39A035360
- Concatenate first n cubes in reverse order.at n=2A038398
- Coordination sequence T5 for Zeolite Code STF.at n=35A038440
- Numerators of continued fraction convergents to sqrt(212).at n=8A041394
- Denominators of continued fraction convergents to sqrt(604).at n=12A042159
- Base-8 palindromes that start with 5.at n=13A043025
- Numbers whose base-14 representation has exactly 4 runs.at n=21A043665
- Numbers k such that the string 3,0 occurs in the base 9 representation of k but not of k-1.at n=38A044278
- Numbers n such that string 7,3 occurs in the base 9 representation of n but not of n-1.at n=37A044317
- Numbers n such that string 8,1 occurs in the base 10 representation of n but not of n-1.at n=29A044413
- Numbers n such that string 3,0 occurs in the base 9 representation of n but not of n+1.at n=38A044659
- Numbers n such that string 8,1 occurs in the base 10 representation of n but not of n+1.at n=29A044794
- Number of partitions of n into at most 1 copy of 1, 2 copies of 2, 3 copies of 3, ... .at n=35A052335