688556689 has 2 divisors, whose sum is σ = 688556690. Its totient is φ = 688556688.

The previous prime is 688556683. The next prime is 688556711. The reversal of 688556689 is 986655886.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 571592464 + 116964225 = 23908^2 + 10815^2 .

It is a cyclic number.

It is not a de Polignac number, because 688556689 - 2²¹ = 686459537 is a prime.

It is a super-2 number, since 2×688556689² = 948220627933285442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (688556683) by changing a digit.

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 as a sum of consecutive naturals, namely, 344278344 + 344278345.

It is an arithmetic number, because the mean of its divisors is an integer number (344278345).

Almost surely, 2^688556689 is an apocalyptic number.

It is an amenable number.

688556689 is a deficient number, since it is larger than the sum of its proper divisors (1).

688556689 is an equidigital number, since it uses as much as digits as its factorization.

688556689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24883200, while the sum is 61.

The square root of 688556689 is about 26240.3637360460. The cubic root of 688556689 is about 883.0390317867.

The spelling of 688556689 in words is "six hundred eighty-eight million, five hundred fifty-six thousand, six hundred eighty-nine".