688137728 has 40 divisors (see below), whose sum is σ = 1391582808. Its totient is φ = 339902464.

The previous prime is 688137719. The next prime is 688137731. The reversal of 688137728 is 827731886.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34400 + ... + 50592.

Almost surely, 2^688137728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 688137728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (695791404).

688137728 is an abundant number, since it is smaller than the sum of its proper divisors (703445080).

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

688137728 is an equidigital number, since it uses as much as digits as its factorization.

688137728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16294 (or 16278 counting only the distinct ones).

The product of its digits is 903168, while the sum is 50.

The square root of 688137728 is about 26232.3793812151. The cubic root of 688137728 is about 882.8598967048.

The spelling of 688137728 in words is "six hundred eighty-eight million, one hundred thirty-seven thousand, seven hundred twenty-eight".