685905 has 16 divisors (see below), whose sum is σ = 1197504. Its totient is φ = 332480.

The previous prime is 685859. The next prime is 685907. The reversal of 685905 is 509586.

It is not a de Polignac number, because 685905 - 2⁸ = 685649 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (685907) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1914 + ... + 2243.

It is an arithmetic number, because the mean of its divisors is an integer number (74844).

2⁶⁸⁵⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

685905 is a deficient number, since it is larger than the sum of its proper divisors (511599).

685905 is a wasteful number, since it uses less digits than its factorization.

685905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4176.

The product of its (nonzero) digits is 10800, while the sum is 33.

The square root of 685905 is about 828.1938178953. The cubic root of 685905 is about 88.1904021312.

The spelling of 685905 in words is "six hundred eighty-five thousand, nine hundred five".