685731 has 4 divisors (see below), whose sum is σ = 914312. Its totient is φ = 457152.

The previous prime is 685723. The next prime is 685733. The reversal of 685731 is 137586.

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

It is not a de Polignac number, because 685731 - 2³ = 685723 is a prime.

It is a super-2 number, since 2×685731² = 940454008722, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (685733) 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 3 ways as a sum of consecutive naturals, for example, 114286 + ... + 114291.

It is an arithmetic number, because the mean of its divisors is an integer number (228578).

2⁶⁸⁵⁷³¹ is an apocalyptic number.

685731 is a deficient number, since it is larger than the sum of its proper divisors (228581).

685731 is a wasteful number, since it uses less digits than its factorization.

685731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228580.

The product of its digits is 5040, while the sum is 30.

The square root of 685731 is about 828.0887633581. The cubic root of 685731 is about 88.1829441365.

The spelling of 685731 in words is "six hundred eighty-five thousand, seven hundred thirty-one".