6689
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 29
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 6690
- 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
- 6688
- Möbius Function
- -1
- Radical
- 6689
- 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
- 44
- 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
- 862
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers that are the sum of 4 positive 7th powers.at n=13A003371
- Primes of the form 2^a + 3^b.at n=46A004051
- Numbers that are the sum of at most 4 positive 7th powers.at n=33A004866
- Primes p such that the NSW number A002315((p-1)/2) is prime.at n=14A005850
- Numbers k such that the continued fraction for sqrt(k) has period 85.at n=4A020424
- 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=42A021005
- Primes that remain prime through 3 iterations of function f(x) = 9x + 8.at n=22A023298
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 9.at n=14A031422
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 40 ones.at n=30A031808
- Start of a string of exactly 2 consecutive (but disjoint) pairs of twin primes.at n=17A035790
- Numerators of continued fraction convergents to sqrt(977).at n=5A042890
- Numbers whose base-9 representation has exactly 5 runs.at n=34A043634
- Primes that yield a different prime when rotated by 180 degrees.at n=24A048890
- Primes whose digits are composite; primes having only {4, 6, 8, 9} as digits.at n=9A051416
- Primes having only {0, 6, 8, 9} as digits.at n=3A053580
- First of four consecutive primes that comprise two sets of twin primes.at n=27A053778
- The primes in A045574.at n=44A057770
- Primes p such that x^19 = 2 has no solution mod p.at n=36A059244
- Primes p such that x^16 = 2 has no solution mod p, but x^8 = 2 has a solution mod p.at n=12A059287
- Primes p such that x^48 = 2 has no solution mod p, but x^24 = 2 has a solution mod p.at n=8A059669