688306391 has 4 divisors (see below), whose sum is σ = 694397712. Its totient is φ = 682215072.

The previous prime is 688306379. The next prime is 688306393. The reversal of 688306391 is 193603886.

688306391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 688306391 - 2¹⁴ = 688290007 is a prime.

It is a super-4 number, since 4×688306391⁴ (a number of 36 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688306393) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3045491 + ... + 3045716.

It is an arithmetic number, because the mean of its divisors is an integer number (173599428).

Almost surely, 2^688306391 is an apocalyptic number.

688306391 is a deficient number, since it is larger than the sum of its proper divisors (6091321).

688306391 is a wasteful number, since it uses less digits than its factorization.

688306391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6091320.

The product of its (nonzero) digits is 186624, while the sum is 44.

The square root of 688306391 is about 26235.5939707871. The cubic root of 688306391 is about 882.9320206556.

The spelling of 688306391 in words is "six hundred eighty-eight million, three hundred six thousand, three hundred ninety-one".