685728 has 36 divisors (see below), whose sum is σ = 1950858. Its totient is φ = 228480.

The previous prime is 685723. The next prime is 685733. The reversal of 685728 is 827586.

It is an interprime number because it is at equal distance from previous prime (685723) and next prime (685733).

It can be written as a sum of positive squares in only one way, i.e., 685584 + 144 = 828^2 + 12^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 685692 and 685701.

It is not an unprimeable number, because it can be changed into a prime (685723) by changing a digit.

685728 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 903 + ... + 1478.

2⁶⁸⁵⁷²⁸ is an apocalyptic number.

It is an amenable number.

685728 is an abundant number, since it is smaller than the sum of its proper divisors (1265130).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

685728 is a wasteful number, since it uses less digits than its factorization.

685728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2397 (or 2386 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 685728 is about 828.0869519561. The cubic root of 685728 is about 88.1828155393.

The spelling of 685728 in words is "six hundred eighty-five thousand, seven hundred twenty-eight".