12809
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 12810
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12808
- Möbius Function
- -1
- Radical
- 12809
- 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
- 125
- 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
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1527
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- From table of maximal epacts e(p) and corresponding primes p, for x_1=2, x_{m+1} = (x_m)^2+1; sequence gives p.at n=31A014424
- Numbers k such that the continued fraction for sqrt(k) has period 91.at n=7A020430
- a(n) = T(2n,n-4), T given by A026725.at n=5A026841
- a(n) = T(2n,n-4), T given by A026736.at n=5A026848
- Number of ways to partition n elements into pie slices of different sizes of at least 2 allowing the pie to be turned over.at n=41A032230
- Primes whose digits can be arranged in increasing cyclic order - to form a substring of 123456789012345678901234567890...at n=28A068710
- Smallest prime of the form 1 followed by a perfect power.at n=12A089773
- Beginning with 2, least number such that concatenation of r copies of a(r), r = 1 to n is prime.at n=37A090559
- Primes which are also prime if their base 64 representation is interpreted as a base 10 number.at n=35A090717
- Balanced primes of order nine.at n=11A096701
- Smallest prime equal to the sum of n distinct squares.at n=31A100559
- Numbers k such that 5*10^k + R_k + 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=3A103006
- a(n) = round(10000*log(n/10)).at n=35A104077
- Primes p such that googol - p is prime.at n=8A108252
- Primes congruent to 17 mod 41.at n=38A142214
- Primes congruent to 38 mod 43.at n=34A142287
- Primes congruent to 25 mod 47.at n=32A142376
- Primes congruent to 20 mod 49.at n=31A142431
- Primes congruent to 36 mod 53.at n=23A142566
- Primes congruent to 49 mod 55.at n=36A142636