685865 has 8 divisors (see below), whose sum is σ = 871560. Its totient is φ = 516352.

The previous prime is 685859. The next prime is 685907. The reversal of 685865 is 568586.

It can be written as a sum of positive squares in 4 ways, for example, as 6889 + 678976 = 83^2 + 824^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 685865 - 2⁴ = 685849 is a prime.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 685865.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3950 + ... + 4119.

It is an arithmetic number, because the mean of its divisors is an integer number (108945).

2⁶⁸⁵⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

685865 is a deficient number, since it is larger than the sum of its proper divisors (185695).

685865 is a wasteful number, since it uses less digits than its factorization.

685865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8091.

The product of its digits is 57600, while the sum is 38.

The square root of 685865 is about 828.1696686066. The cubic root of 685865 is about 88.1886877613.

The spelling of 685865 in words is "six hundred eighty-five thousand, eight hundred sixty-five".