721857680 has 20 divisors (see below), whose sum is σ = 1678319292. Its totient is φ = 288743040.

The previous prime is 721857613. The next prime is 721857683. The reversal of 721857680 is 86758127.

It can be written as a sum of positive squares in 2 ways, for example, as 248882176 + 472975504 = 15776^2 + 21748^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (721857683) 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, 4511531 + ... + 4511690.

Almost surely, 2^721857680 is an apocalyptic number.

It is an amenable number.

721857680 is an abundant number, since it is smaller than the sum of its proper divisors (956461612).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721857680 is a wasteful number, since it uses less digits than its factorization.

721857680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9023234 (or 9023228 counting only the distinct ones).

The product of its (nonzero) digits is 188160, while the sum is 44.

The square root of 721857680 is about 26867.4092535920. The cubic root of 721857680 is about 897.0511221256.

The spelling of 721857680 in words is "seven hundred twenty-one million, eight hundred fifty-seven thousand, six hundred eighty".