2687
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 23
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2688
- 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
- 2686
- Möbius Function
- -1
- Radical
- 2687
- 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
- 97
- 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
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 390
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- a(n) = least primitive factor of 2^(2n+1) - 1.at n=39A002184
- Numbers k such that (14^k - 1)/13 is prime.at n=5A006032
- Coordination sequence T3 for Zeolite Code FER.at n=32A008108
- Coordination sequence T1 for Zeolite Code LTN.at n=36A008140
- Numbers n such that phi(n + 9) | sigma(n) for n not congruent to 0 (mod 3).at n=43A015849
- Smallest prime factor of Mersenne numbers 2^p-1, where p is prime.at n=21A016047
- a(n)-th prime is sum of first k primes for some k.at n=9A020641
- a(n)-th nonsquarefree is sum of first k nonsquarefrees for some k.at n=31A020644
- Let q_k=p(p+2) be product of k-th pair of twin primes; sequence gives values of p such that (q_k)^2 > q_{k-i}q_{k+i} for all 1 <= i <= k-1.at n=25A021005
- Initial members of prime triples (p, p+2, p+6).at n=28A022004
- Primes that remain prime through 2 iterations of function f(x) = 8x + 7.at n=24A023263
- Primes that are palindromic in base 14.at n=29A029981
- a(n) = prime(10*n).at n=38A031343
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 51.at n=9A031549
- "BGK" (reversible, element, unlabeled) transform of 2,2,2,2,...at n=12A032061
- Primes of form x^2+86*y^2.at n=15A033255
- Start of a string of exactly 1 consecutive (but disjoint) pair of twin primes.at n=45A035789
- Partial sums of Fibonacci-lucky numbers.at n=46A039677
- Numerators of continued fraction convergents to sqrt(800).at n=4A042542
- a(n) = (s(n) + 1)/5, where s(n) = n-th base-5 palindrome that starts with 4.at n=44A043053