8139332721 has 16 divisors (see below), whose sum is σ = 11715845120. Its totient is φ = 4996563840.

The previous prime is 8139332717. The next prime is 8139332723. The reversal of 8139332721 is 1272339318.

It is not a de Polignac number, because 8139332721 - 2² = 8139332717 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 8139332721.

It is not an unprimeable number, because it can be changed into a prime (8139332723) 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, 239185 + ... + 271086.

It is an arithmetic number, because the mean of its divisors is an integer number (732240320).

Almost surely, 2^8139332721 is an apocalyptic number.

It is an amenable number.

8139332721 is a deficient number, since it is larger than the sum of its proper divisors (3576512399).

8139332721 is a wasteful number, since it uses less digits than its factorization.

8139332721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 510696.

The product of its digits is 54432, while the sum is 39.

The square root of 8139332721 is about 90218.2504873598. The cubic root of 8139332721 is about 2011.5442964829.

The spelling of 8139332721 in words is "eight billion, one hundred thirty-nine million, three hundred thirty-two thousand, seven hundred twenty-one".