6871
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 6872
- 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
- 6870
- Möbius Function
- -1
- Radical
- 6871
- 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
- 150
- 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
- 885
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers k such that (1,k) is "good".at n=43A000696
- Quintan primes: p = (x^5 + y^5)/(x + y).at n=12A002650
- G.f.: x^2*(x^2 + x + 1)/(x^4 - 2*x + 1).at n=13A027084
- 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 81.at n=25A031579
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 50 ones.at n=17A031818
- Primes that are concatenations of n with n + 3.at n=8A032626
- Lucky numbers that are decimal concatenations of n with n + 3.at n=9A032653
- Schoenheim bound L_1(n,8,7).at n=11A036835
- Integers n such that A047988(n)=3.at n=31A047986
- Primes p such that pp'-2 is prime, where p' denotes the next prime after p.at n=39A048797
- Values of A (the short leg) of a Pythagorean triangle with A and C (the hypotenuse) both prime and part of a twin prime.at n=22A051642
- Primes of the form 30*p + 1 where p is also prime.at n=21A051646
- Primes of form prime(1) + ... + prime(k) + 1.at n=12A053845
- Prime lucky numbers k (from A031157) such that nextprime(k)=nextlucky(k).at n=11A057698
- Numbers which yield a prime whenever a 1 is inserted anywhere in them (including at the beginning or end).at n=56A068679
- Primes which yield a prime whenever a 1 is inserted anywhere in them (including at the beginning or end).at n=17A069246
- Diagonal of triangle in A082737.at n=23A082738
- Primes such that successive differences are distinct palindromes.at n=27A087582
- Numbers k such that the k-th prime is of the form 2*j^2 + 1.at n=28A090612
- First of 9 consecutive primes in a 3 X 3 spiral wherein the mean of all 8 sums is prime.at n=24A094454