688357391 has 2 divisors, whose sum is σ = 688357392. Its totient is φ = 688357390.

The previous prime is 688357349. The next prime is 688357451. The reversal of 688357391 is 193753886.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-688357391 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688357321) 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, 344178695 + 344178696.

It is an arithmetic number, because the mean of its divisors is an integer number (344178696).

Almost surely, 2^688357391 is an apocalyptic number.

688357391 is a deficient number, since it is larger than the sum of its proper divisors (1).

688357391 is an equidigital number, since it uses as much as digits as its factorization.

688357391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1088640, while the sum is 50.

The square root of 688357391 is about 26236.5659147686. The cubic root of 688357391 is about 882.9538270398.

The spelling of 688357391 in words is "six hundred eighty-eight million, three hundred fifty-seven thousand, three hundred ninety-one".