688721773 has 4 divisors (see below), whose sum is σ = 689719168. Its totient is φ = 687724380.

The previous prime is 688721753. The next prime is 688721807. The reversal of 688721773 is 377127886.

688721773 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 688721773 - 2⁵ = 688721741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688721753) 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, 497661 + ... + 499042.

It is an arithmetic number, because the mean of its divisors is an integer number (172429792).

Almost surely, 2^688721773 is an apocalyptic number.

It is an amenable number.

688721773 is a deficient number, since it is larger than the sum of its proper divisors (997395).

688721773 is an equidigital number, since it uses as much as digits as its factorization.

688721773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 997394.

The product of its digits is 790272, while the sum is 49.

The square root of 688721773 is about 26243.5091594093. The cubic root of 688721773 is about 883.1095967667.

The spelling of 688721773 in words is "six hundred eighty-eight million, seven hundred twenty-one thousand, seven hundred seventy-three".