685915 has 4 divisors (see below), whose sum is σ = 823104. Its totient is φ = 548728.

The previous prime is 685907. The next prime is 685939. The reversal of 685915 is 519586.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 685915 - 2³ = 685907 is a prime.

It is a Duffinian number.

685915 is a lucky number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68587 + ... + 68596.

It is an arithmetic number, because the mean of its divisors is an integer number (205776).

2⁶⁸⁵⁹¹⁵ is an apocalyptic number.

685915 is a deficient number, since it is larger than the sum of its proper divisors (137189).

685915 is a wasteful number, since it uses less digits than its factorization.

685915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137188.

The product of its digits is 10800, while the sum is 34.

The square root of 685915 is about 828.1998551074. The cubic root of 685915 is about 88.1908307133.

It can be divided in two parts, 685 and 915, that added together give a square (1600 = 40²).

The spelling of 685915 in words is "six hundred eighty-five thousand, nine hundred fifteen".