993128721 has 16 divisors (see below), whose sum is σ = 1427991936. Its totient is φ = 610315776.

The previous prime is 993128701. The next prime is 993128743. The reversal of 993128721 is 127821399.

993128721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 993128721 - 2⁹ = 993128209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (993128701) 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, 11841 + ... + 46113.

It is an arithmetic number, because the mean of its divisors is an integer number (89249496).

Almost surely, 2^993128721 is an apocalyptic number.

It is an amenable number.

993128721 is a deficient number, since it is larger than the sum of its proper divisors (434863215).

993128721 is a wasteful number, since it uses less digits than its factorization.

993128721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35032.

The product of its digits is 54432, while the sum is 42.

The square root of 993128721 is about 31513.9448657257. The cubic root of 993128721 is about 997.7043074955.

The spelling of 993128721 in words is "nine hundred ninety-three million, one hundred twenty-eight thousand, seven hundred twenty-one".