1919
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 2040
- Proper Divisor Sum (Aliquot Sum)
- 121
- 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
- 1800
- Möbius Function
- 1
- Radical
- 1919
- 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
- 130
- 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
- Smallest number with reciprocal of period length n in decimal (base 10).at n=36A003060
- Coordination sequence T1 for Zeolite Code ATV.at n=28A008043
- Coordination sequence T1 for Zeolite Code MEP.at n=26A008157
- Coordination sequence T4 for Zeolite Code MFS.at n=27A008176
- Coordination sequence T2 for Zeolite Code PAU.at n=32A008220
- Doublets: base-10 representation is the juxtaposition of two identical strings.at n=18A020338
- Main diagonal of Wythoff array: w(n,n)=[ n*tau ]F(n+1)+(n-1)F(n), where tau=(1+sqrt(5))/2, F(n) = Fibonacci numbers.at n=9A020941
- Fibonacci sequence beginning 2, 7.at n=13A022113
- a(n) = Sum_{k = 1..n} k*floor((n + prime(k))/k).at n=27A024929
- a(n) = greatest number in row n of A026098 that is not a positive power of 2.at n=41A026104
- a(n) = Sum_{i=0..n} Sum_{j=0..n} T(i,j), T given by A026769.at n=9A026778
- a(n) = (1/2)*(n-th largest even number in array T given by A027170).at n=49A027184
- Binary expansion contains a single 0.at n=48A030130
- Numbers whose base-4 representation has 4 fewer 0's than 3's.at n=13A031469
- Numbers whose base-10 representation has 2 fewer 0's than 9's.at n=33A031500
- Fractional part of square root of a(n) starts with 8: first term of runs.at n=41A034114
- Number of partitions of n into parts 5k+1 or 5k+2.at n=47A035371
- First differences of A035410.at n=45A035420
- Number of partitions in parts not of the form 11k, 11k+1 or 11k-1. Also number of partitions with no part of size 1 and differences between parts at distance 4 are greater than 1.at n=35A035944
- Number of partitions satisfying (cn(0,5) <= cn(1,5) = cn(4,5) and cn(1,5) <= cn(2,5) and cn(1,5) <= cn(3,5)).at n=43A036819