688656686 has 16 divisors (see below), whose sum is σ = 1052534736. Its totient is φ = 337852416.

The previous prime is 688656671. The next prime is 688656697. The reversal of 688656686 is 686656886.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24440 + ... + 44436.

It is an arithmetic number, because the mean of its divisors is an integer number (65783421).

Almost surely, 2^688656686 is an apocalyptic number.

688656686 is a deficient number, since it is larger than the sum of its proper divisors (363878050).

688656686 is a wasteful number, since it uses less digits than its factorization.

688656686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20323.

The product of its digits is 19906560, while the sum is 59.

The square root of 688656686 is about 26242.2690710998. The cubic root of 688656686 is about 883.0817767445.

The spelling of 688656686 in words is "six hundred eighty-eight million, six hundred fifty-six thousand, six hundred eighty-six".