685812721 has 16 divisors (see below), whose sum is σ = 776982528. Its totient is φ = 599691600.

The previous prime is 685812713. The next prime is 685812763. The reversal of 685812721 is 127218586.

685812721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 685812721 - 2³ = 685812713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (685812791) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50926 + ... + 62968.

It is an arithmetic number, because the mean of its divisors is an integer number (48561408).

Almost surely, 2^685812721 is an apocalyptic number.

It is an amenable number.

685812721 is a deficient number, since it is larger than the sum of its proper divisors (91169807).

685812721 is a wasteful number, since it uses less digits than its factorization.

685812721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12252.

The product of its digits is 53760, while the sum is 40.

The square root of 685812721 is about 26188.0262906543. The cubic root of 685812721 is about 881.8644702224.

The spelling of 685812721 in words is "six hundred eighty-five million, eight hundred twelve thousand, seven hundred twenty-one".