688735631 has 2 divisors, whose sum is σ = 688735632. Its totient is φ = 688735630.

The previous prime is 688735627. The next prime is 688735633. The reversal of 688735631 is 136537886.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 688735631 - 2² = 688735627 is a prime.

It is a super-2 number, since 2×688735631² = 948713538817936322, which contains 22 as substring.

Together with 688735633, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688735633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344367815 + 344367816.

It is an arithmetic number, because the mean of its divisors is an integer number (344367816).

Almost surely, 2^688735631 is an apocalyptic number.

688735631 is a deficient number, since it is larger than the sum of its proper divisors (1).

688735631 is an equidigital number, since it uses as much as digits as its factorization.

688735631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 725760, while the sum is 47.

The square root of 688735631 is about 26243.7731852720. The cubic root of 688735631 is about 883.1155198410.

The spelling of 688735631 in words is "six hundred eighty-eight million, seven hundred thirty-five thousand, six hundred thirty-one".