389872721 has 4 divisors (see below), whose sum is σ = 445568832. Its totient is φ = 334176612.

The previous prime is 389872711. The next prime is 389872739. The reversal of 389872721 is 127278983.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 389872721 - 2⁶ = 389872657 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (389872711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27848045 + ... + 27848058.

It is an arithmetic number, because the mean of its divisors is an integer number (111392208).

Almost surely, 2^389872721 is an apocalyptic number.

It is an amenable number.

389872721 is a deficient number, since it is larger than the sum of its proper divisors (55696111).

389872721 is an equidigital number, since it uses as much as digits as its factorization.

389872721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55696110.

The product of its digits is 338688, while the sum is 47.

The square root of 389872721 is about 19745.1948838192. The cubic root of 389872721 is about 730.5348685321.

The spelling of 389872721 in words is "three hundred eighty-nine million, eight hundred seventy-two thousand, seven hundred twenty-one".