8388721 has 16 divisors (see below), whose sum is σ = 9704448. Its totient is φ = 7176400.

The previous prime is 8388697. The next prime is 8388733. The reversal of 8388721 is 1278838.

It is not a de Polignac number, because 8388721 - 2⁷ = 8388593 is a prime.

It is a d-powerful number, because it can be written as 8 + 3⁴ + 8 + 8 + 7 + 2²³ + 1 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8388761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17730 + ... + 18196.

It is an arithmetic number, because the mean of its divisors is an integer number (606528).

Almost surely, 2^8388721 is an apocalyptic number.

It is an amenable number.

8388721 is a deficient number, since it is larger than the sum of its proper divisors (1315727).

8388721 is a wasteful number, since it uses less digits than its factorization.

8388721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 572.

The product of its digits is 21504, while the sum is 37.

The square root of 8388721 is about 2896.3288832589. The cubic root of 8388721 is about 203.1882470030.

It can be divided in two parts, 838 and 8721, that added together give a palindrome (9559).

The spelling of 8388721 in words is "eight million, three hundred eighty-eight thousand, seven hundred twenty-one".