688138764 has 12 divisors (see below), whose sum is σ = 1605657144. Its totient is φ = 229379584.

The previous prime is 688138757. The next prime is 688138783. The reversal of 688138764 is 467831886.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28672437 + ... + 28672460.

It is an arithmetic number, because the mean of its divisors is an integer number (133804762).

Almost surely, 2^688138764 is an apocalyptic number.

It is an amenable number.

688138764 is an abundant number, since it is smaller than the sum of its proper divisors (917518380).

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

688138764 is a wasteful number, since it uses less digits than its factorization.

688138764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57344904 (or 57344902 counting only the distinct ones).

The product of its digits is 1548288, while the sum is 51.

The square root of 688138764 is about 26232.3991277961. The cubic root of 688138764 is about 882.8603397568.

It can be divided in two parts, 68813 and 8764, that added together give a palindrome (77577).

The spelling of 688138764 in words is "six hundred eighty-eight million, one hundred thirty-eight thousand, seven hundred sixty-four".