688138660 has 24 divisors (see below), whose sum is σ = 1576463616. Its totient is φ = 250232160.

The previous prime is 688138657. The next prime is 688138669. The reversal of 688138660 is 66831886.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 688138660.

It is not an unprimeable number, because it can be changed into a prime (688138669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1563732 + ... + 1564171.

It is an arithmetic number, because the mean of its divisors is an integer number (65685984).

Almost surely, 2^688138660 is an apocalyptic number.

It is an amenable number.

688138660 is an abundant number, since it is smaller than the sum of its proper divisors (888324956).

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

688138660 is a wasteful number, since it uses less digits than its factorization.

688138660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3127923 (or 3127921 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 46.

The square root of 688138660 is about 26232.3971455146. The cubic root of 688138660 is about 882.8602952806.

The spelling of 688138660 in words is "six hundred eighty-eight million, one hundred thirty-eight thousand, six hundred sixty".