688175981 has 2 divisors, whose sum is σ = 688175982. Its totient is φ = 688175980.

The previous prime is 688175977. The next prime is 688176011. The reversal of 688175981 is 189571886.

688175981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 590976100 + 97199881 = 24310^2 + 9859^2 .

It is a cyclic number.

It is not a de Polignac number, because 688175981 - 2² = 688175977 is a prime.

It is a super-2 number, since 2×688175981² = 947172361650624722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688175951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344087990 + 344087991.

It is an arithmetic number, because the mean of its divisors is an integer number (344087991).

Almost surely, 2^688175981 is an apocalyptic number.

It is an amenable number.

688175981 is a deficient number, since it is larger than the sum of its proper divisors (1).

688175981 is an equidigital number, since it uses as much as digits as its factorization.

688175981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 967680, while the sum is 53.

The square root of 688175981 is about 26233.1084890830. The cubic root of 688175981 is about 882.8762555491.

The spelling of 688175981 in words is "six hundred eighty-eight million, one hundred seventy-five thousand, nine hundred eighty-one".