6551
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 6552
- 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
- 6550
- Möbius Function
- -1
- Radical
- 6551
- 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
- 137
- 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
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 846
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- 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=40A021005
- Number of 2's in all partitions of n.at n=27A024786
- Numbers whose least quadratic nonresidue (A020649) is 17.at n=4A025026
- 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 79.at n=31A031577
- Number of partitions of n with equal number of parts congruent to each of 0, 1 and 3 (mod 5).at n=55A035573
- Numbers having three 8's in base 9.at n=23A043487
- Numbers whose base-3 representation contains no 0's and exactly one 1.at n=33A044966
- Primes of the form n*phi(n)-1 where phi is the Euler function (in order of appearance).at n=38A046078
- Automorphic primes: p such that p^p ends with the digits of p.at n=45A052228
- Primes such that the sum of the factorials of the digits is a perfect square.at n=21A052279
- Birthday set of order 9: i.e., numbers congruent to +- 1 modulo 2, 3, 4, 5, 6, 7, 8 and 9.at n=41A057541
- Primes with 17 as smallest positive primitive root.at n=9A061329
- Primes with either no internal digits or all internal digits are 5.at n=48A069680
- Initial terms of rows of A077321.at n=49A077322
- Prime numbers occurring at integer Pythagorean distance (radius) from 1 in Ulam square prime-spiral. Primes on axes are excluded.at n=16A078765
- Near twin primes of order 18: twin primes (p, p+2) such that p+18 and p+20 are primes.at n=18A079304
- Primes p such that 13 is the largest of all prime factors of the numbers between p and the next prime (cf. A052248).at n=13A080188
- a(n) = (prime(n)+1)*n - 1.at n=38A083723
- Number of monomials in expansion of permanent of an n X n Toeplitz matrix [t(|i-j|) ] in terms of its entries.at n=9A086647
- Smallest member of a pair of consecutive twin prime pairs that have one prime between them.at n=31A089629