688687924 has 6 divisors (see below), whose sum is σ = 1205203874. Its totient is φ = 344343960.

The previous prime is 688687907. The next prime is 688687931. The reversal of 688687924 is 429786886.

It can be written as a sum of positive squares in only one way, i.e., 648619024 + 40068900 = 25468^2 + 6330^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86085987 + ... + 86085994.

Almost surely, 2^688687924 is an apocalyptic number.

It is an amenable number.

688687924 is a deficient number, since it is larger than the sum of its proper divisors (516515950).

688687924 is a wasteful number, since it uses less digits than its factorization.

688687924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172171985 (or 172171983 counting only the distinct ones).

The product of its digits is 9289728, while the sum is 58.

The square root of 688687924 is about 26242.8642491630. The cubic root of 688687924 is about 883.0951289668.

The spelling of 688687924 in words is "six hundred eighty-eight million, six hundred eighty-seven thousand, nine hundred twenty-four".