1905
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
- 8
- Divisor Sum
- 3072
- Proper Divisor Sum (Aliquot Sum)
- 1167
- 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
- 1008
- Möbius Function
- -1
- Radical
- 1905
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 37
- 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
- Fermat pseudoprimes to base 2, also called Sarrus numbers or Poulet numbers.at n=6A001567
- Number of filaments with n square cells.at n=12A002013
- Divisors of 2^28 - 1.at n=20A003536
- Convolution of A002024 with itself.at n=48A004797
- Euler pseudoprimes: composite numbers n such that 2^((n-1)/2) == +-1 (mod n).at n=4A006970
- Composite numbers k such that k == +-1 (mod 8) and 2^((k-1)/2) == 1 (mod k).at n=3A006971
- Coordination sequence T3 for Zeolite Code AEI.at n=33A008003
- Coordination sequence T2 for Zeolite Code DOH.at n=27A008079
- Coordination sequence T2 for Zeolite Code EUO.at n=27A008097
- Coordination sequence T3 for Zeolite Code EUO.at n=27A008098
- Coordination sequence T1 for Zeolite Code LOV.at n=29A008134
- Expansion of (1+x^5)/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)).at n=49A008766
- sec(arcsin(x)*exp(x))=1+1/2!*x^2+6/3!*x^3+33/4!*x^4+220/5!*x^5...at n=6A012326
- a(n) = a(n-1) + 7*a(n-2), a(0)=0, a(1)=1.at n=8A015442
- Number of (unordered) triples of integers from [1,n] with no common factors between pairs.at n=33A015617
- Odd numbers k such that phi(k) | sigma_3(k).at n=35A015809
- Define the sequence S(a_0,a_1) by a_{n+2} is the least integer such that a_{n+2}/a_{n+1}>a_{n+1}/a_n for n >= 0. This is S(4,8).at n=8A019479
- Fermat pseudoprimes to base 4.at n=17A020136
- Pseudoprimes to base 8.at n=31A020137
- Pseudoprimes to base 16.at n=23A020144