688725591 has 8 divisors (see below), whose sum is σ = 923431680. Its totient is φ = 456584952.

The previous prime is 688725571. The next prime is 688725649. The reversal of 688725591 is 195527886.

688725591 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 688725591 - 2⁷ = 688725463 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688725551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 640735 + ... + 641808.

It is an arithmetic number, because the mean of its divisors is an integer number (115428960).

Almost surely, 2^688725591 is an apocalyptic number.

688725591 is a deficient number, since it is larger than the sum of its proper divisors (234706089).

688725591 is a wasteful number, since it uses less digits than its factorization.

688725591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1282725.

The product of its digits is 1209600, while the sum is 51.

The square root of 688725591 is about 26243.5819011049. The cubic root of 688725591 is about 883.1112286333. Note that the first 3 decimals are identical.

The spelling of 688725591 in words is "six hundred eighty-eight million, seven hundred twenty-five thousand, five hundred ninety-one".