2805
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 5184
- Proper Divisor Sum (Aliquot Sum)
- 2379
- 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
- 1280
- Möbius Function
- 1
- Radical
- 2805
- Omega Function (Ω)
- 4
- 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
- 84
- 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
- Odd squarefree numbers with an even number of prime factors that have no prime factors greater than 31.at n=52A002557
- Coordination sequence T3 for Zeolite Code AFT.at n=40A008028
- Coordination sequence T2 for Zeolite Code RUT.at n=35A009898
- a(n) = floor( n*(n-1)*(n-2)/14 ).at n=35A011896
- Orders of cyclotomic polynomials containing a coefficient the absolute value of which is >= 3.at n=38A013591
- Orders of cyclotomic polynomials containing a coefficient the absolute value of which is >= 4.at n=9A013592
- Orders of cyclotomic polynomials containing a coefficient the absolute value of which is >= 5.at n=3A013593
- Smallest order of cyclotomic polynomial containing n or -n as a coefficient.at n=5A013594
- Pseudoprimes to base 67.at n=29A020195
- Pseudoprimes to base 89.at n=36A020217
- Pseudoprimes to base 98.at n=26A020226
- a(n) = n*(25*n - 1)/2.at n=15A022282
- 5 times triangular numbers: a(n) = 5*n*(n+1)/2.at n=33A028895
- Every run of digits of n in base 4 has length 2.at n=28A033002
- a(n)=number of Gaussian integers z=a+bi satisfying |z|<=n, b>=0.at n=42A036695
- Odd numbers m such that there exists an even number k < m with phi(k) = phi(m).at n=25A036798
- Number of partitions satisfying (cn(0,5) = 0 and cn(2,5) = cn(3,5)).at n=41A036815
- Maximal base 7 run length is 4.at n=11A037991
- a(n) = (n-3)*A006918(n-2)/2 for n >= 2, with a(0) = a(1) = 0.at n=20A038376
- Numbers whose base-7 representation contains exactly four 1's.at n=8A043400