8128364721 has 16 divisors (see below), whose sum is σ = 11133633984. Its totient is φ = 5271079104.

The previous prime is 8128364701. The next prime is 8128364773. The reversal of 8128364721 is 1274638218.

It is not a de Polignac number, because 8128364721 - 2⁷ = 8128364593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (8128364701) 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, 583975 + ... + 597731.

It is an arithmetic number, because the mean of its divisors is an integer number (695852124).

Almost surely, 2^8128364721 is an apocalyptic number.

It is an amenable number.

8128364721 is a deficient number, since it is larger than the sum of its proper divisors (3005269263).

8128364721 is a wasteful number, since it uses less digits than its factorization.

8128364721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19120.

The product of its digits is 129024, while the sum is 42.

The square root of 8128364721 is about 90157.4440686957. Note that the first 3 decimals coincide. The cubic root of 8128364721 is about 2010.6403511578.

The spelling of 8128364721 in words is "eight billion, one hundred twenty-eight million, three hundred sixty-four thousand, seven hundred twenty-one".