721671728 has 20 divisors (see below), whose sum is σ = 1446455040. Its totient is φ = 348393024.

The previous prime is 721671707. The next prime is 721671779. The reversal of 721671728 is 827176127.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 777200 + ... + 778127.

It is an arithmetic number, because the mean of its divisors is an integer number (72322752).

Almost surely, 2^721671728 is an apocalyptic number.

It is an amenable number.

721671728 is an abundant number, since it is smaller than the sum of its proper divisors (724783312).

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

721671728 is a wasteful number, since it uses less digits than its factorization.

721671728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1555364 (or 1555358 counting only the distinct ones).

The product of its digits is 65856, while the sum is 41.

The square root of 721671728 is about 26863.9484811894. The cubic root of 721671728 is about 896.9740881153.

The spelling of 721671728 in words is "seven hundred twenty-one million, six hundred seventy-one thousand, seven hundred twenty-eight".