688332644 has 6 divisors (see below), whose sum is σ = 1204582134. Its totient is φ = 344166320.

The previous prime is 688332637. The next prime is 688332647. The reversal of 688332644 is 446233886.

It can be written as a sum of positive squares in only one way, i.e., 404814400 + 283518244 = 20120^2 + 16838^2 .

It is a junction number, because it is equal to n+sod(n) for n = 688332595 and 688332604.

It is not an unprimeable number, because it can be changed into a prime (688332647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86041577 + ... + 86041584.

It is an arithmetic number, because the mean of its divisors is an integer number (200763689).

Almost surely, 2^688332644 is an apocalyptic number.

It is an amenable number.

688332644 is a deficient number, since it is larger than the sum of its proper divisors (516249490).

688332644 is a wasteful number, since it uses less digits than its factorization.

688332644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172083165 (or 172083163 counting only the distinct ones).

The product of its digits is 663552, while the sum is 44.

The square root of 688332644 is about 26236.0942977418. The cubic root of 688332644 is about 882.9432459471.

The spelling of 688332644 in words is "six hundred eighty-eight million, three hundred thirty-two thousand, six hundred forty-four".