688731904 has 108 divisors (see below), whose sum is σ = 1630776784. Its totient is φ = 284368896.

The previous prime is 688731871. The next prime is 688731917. The reversal of 688731904 is 409137886.

It is a happy number.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 1506844 + ... + 1507300.

Almost surely, 2^688731904 is an apocalyptic number.

688731904 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 688731904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (815388392).

688731904 is an abundant number, since it is smaller than the sum of its proper divisors (942044880).

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

688731904 is an equidigital number, since it uses as much as digits as its factorization.

688731904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538 (or 495 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 46.

The square root of 688731904 is about 26243.7021778559. The cubic root of 688731904 is about 883.1139268846.

The spelling of 688731904 in words is "six hundred eighty-eight million, seven hundred thirty-one thousand, nine hundred four".