1889
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1890
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 1888
- Möbius Function
- -1
- Radical
- 1889
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 81
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 290
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes p == 3, 9, 11 (mod 20) such that 2p+1 is also prime.at n=28A000355
- Smallest nonnegative number that is the sum of 3 squares in exactly n ways.at n=18A000437
- Smallest number that is the sum of 3 squares in at least n ways.at n=18A000451
- Primes p such that the multiplicative order of 2 modulo p is (p-1)/4.at n=14A001134
- Expansion of 1/((1-x)^2*(1-x^2)*(1-x^5)*(1-x^10)*(1-x^20)).at n=36A001305
- Values of m in the discriminant D = -4*m leading to a new maximum of the L-function of the Dirichlet series L(1) = Sum_{k=1..oo} Kronecker(D,k)/k.at n=15A003420
- Class 4- primes (for definition see A005109).at n=44A005112
- Numbers n such that n, 2n+1, and 4n+3 all prime.at n=17A007700
- Primes p == 1 (mod 8), p = a^2 + 64*b^2 such that y^2 = x^3 + p*x has rank 2.at n=25A007766
- Coordination sequence T2 for Zeolite Code AET.at n=30A008008
- Coordination sequence T3 for Zeolite Code AET.at n=30A008009
- Coordination sequence T2 for Zeolite Code LOV.at n=29A008135
- a(n) = floor( n*(n-1)*(n-2)/19 ).at n=34A011901
- Pisot sequence E(10,18), a(n)=[ a(n-1)^2/a(n-2)+1/2 ].at n=9A014006
- a(n) = n^2 + 3*n - 1.at n=42A014209
- Primes p == 1 mod 8 such that 2 and -2 are both 4th powers (one implies other) mod p.at n=32A014754
- Six iterations of Reverse and Add are needed to reach a palindrome.at n=34A015984
- Expansion of 1/(1-x^7-x^8-x^9-x^10-x^11-x^12-x^13-x^14-x^15-x^16-x^17).at n=45A017866
- Numbers k such that the continued fraction for sqrt(k) has period 27.at n=7A020366
- Smallest nonempty set S containing prime divisors of 8k+3 for each k in S.at n=48A020617