6721418728 has 16 divisors (see below), whose sum is σ = 12718282500. Its totient is φ = 3329876736.

The previous prime is 6721418659. The next prime is 6721418771. The reversal of 6721418728 is 8278141276.

It can be written as a sum of positive squares in 2 ways, for example, as 5621700484 + 1099718244 = 74978^2 + 33162^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3853153 + ... + 3854896.

Almost surely, 2^6721418728 is an apocalyptic number.

It is an amenable number.

6721418728 is a deficient number, since it is larger than the sum of its proper divisors (5996863772).

6721418728 is a wasteful number, since it uses less digits than its factorization.

6721418728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7708164 (or 7708160 counting only the distinct ones).

The product of its digits is 301056, while the sum is 46.

The square root of 6721418728 is about 81984.2590257423. The cubic root of 6721418728 is about 1887.2103828723.

The spelling of 6721418728 in words is "six billion, seven hundred twenty-one million, four hundred eighteen thousand, seven hundred twenty-eight".