688828661 has 8 divisors (see below), whose sum is σ = 736041240. Its totient is φ = 642359808.

The previous prime is 688828631. The next prime is 688828681. The reversal of 688828661 is 166828886.

688828661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 85192900 + 603635761 = 9230^2 + 24569^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 688828661 - 2¹⁰ = 688827637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688828601) 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, 184016 + ... + 187721.

It is an arithmetic number, because the mean of its divisors is an integer number (92005155).

Almost surely, 2^688828661 is an apocalyptic number.

It is an amenable number.

688828661 is a deficient number, since it is larger than the sum of its proper divisors (47212579).

688828661 is a wasteful number, since it uses less digits than its factorization.

688828661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371863.

The product of its digits is 1769472, while the sum is 53.

The square root of 688828661 is about 26245.5455458636. The cubic root of 688828661 is about 883.1552799146.

The spelling of 688828661 in words is "six hundred eighty-eight million, eight hundred twenty-eight thousand, six hundred sixty-one".