688091391 has 48 divisors (see below), whose sum is σ = 1122593472. Its totient is φ = 402969600.

The previous prime is 688091389. The next prime is 688091399. The reversal of 688091391 is 193190886.

It is not a de Polignac number, because 688091391 - 2¹ = 688091389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688091399) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 648001 + ... + 649061.

It is an arithmetic number, because the mean of its divisors is an integer number (23387364).

Almost surely, 2^688091391 is an apocalyptic number.

688091391 is a deficient number, since it is larger than the sum of its proper divisors (434502081).

688091391 is a wasteful number, since it uses less digits than its factorization.

688091391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1344 (or 1341 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 45.

The square root of 688091391 is about 26231.4961639629. The cubic root of 688091391 is about 882.8400799368.

The spelling of 688091391 in words is "six hundred eighty-eight million, ninety-one thousand, three hundred ninety-one".