686
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 1200
- Proper Divisor Sum (Aliquot Sum)
- 514
- 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
- 294
- Möbius Function
- 0
- Radical
- 14
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 2
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
- 126
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Names
- German
- sechshundertsechsundachtzig· ordinal: sechshundertsechsundachtzigste
- English
- six hundred eighty-six· ordinal: six hundred eighty-sixth
- Spanish
- seiscientos ochenta y seis· ordinal: 686º
- French
- six cent quatre-vingt-six· ordinal: six cent quatre-vingt-sixième
- Italian
- seicentoottantasei· ordinal: 686º
- Latin
- sescenti octoginta sex· ordinal: 686.
- Portuguese
- seiscentos e oitenta e seis· ordinal: 686º
Appears in sequences
- Convolution of A000203 with itself.at n=10A000385
- Numbers in which every digit contains at least one loop (version 1).at n=25A001743
- Number of 4-line partitions of n decreasing across rows.at n=14A003292
- a(n+1) = 1 + a( floor(n/1) ) + a( floor(n/2) ) + ... + a( floor(n/n) ).at n=19A003318
- Numbers that are the sum of 2 positive cubes.at n=32A003325
- Numbers of form 2^i*7^j, with i, j >= 0.at n=22A003591
- Expansion of (1-x)/( (1+x)*(1-2*x)*(1-3*x)*(1-4*x)*(1-5*x)).at n=3A004058
- Sums of two nonnegative cubes.at n=41A004999
- a(n) = a(n-1) + a(n-6), with a(i) = 1 for i = 0..5.at n=29A005708
- Number of acyclic tertiary alcohols with n carbon atoms.at n=7A005956
- G.f.: 2*(1-x^3)/((1-x)^5*(1+x)^2).at n=12A005996
- Numbers k such that k^16 + 1 is prime.at n=30A006313
- Number of nonseparable toroidal tree-rooted maps with n + 2 edges and n + 1 vertices.at n=5A006414
- Permutation arrays of period n.at n=8A006841
- Number of strict 7th-order maximal independent sets in path graph.at n=43A007386
- Inverse Moebius transform of triangular numbers.at n=29A007437
- Prime(n)*...*prime(a(n)) is the least product of consecutive primes that is non-deficient.at n=18A007684
- Number of partitions of n in which no part occurs just once.at n=35A007690
- Prime(n)*...*prime(a(n)) is the least product of consecutive primes which is abundant.at n=18A007707
- Coordination sequence T1 for Zeolite Code ABW and ATN.at n=18A008000