8389721 has 8 divisors (see below), whose sum is σ = 8997120. Its totient is φ = 7795008.

The previous prime is 8389709. The next prime is 8389727. The reversal of 8389721 is 1279838.

8389721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 8389721 - 2⁶ = 8389657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8389727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1781 + ... + 4466.

It is an arithmetic number, because the mean of its divisors is an integer number (1124640).

Almost surely, 2^8389721 is an apocalyptic number.

It is an amenable number.

8389721 is a deficient number, since it is larger than the sum of its proper divisors (607399).

8389721 is a wasteful number, since it uses less digits than its factorization.

8389721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6343.

The product of its digits is 24192, while the sum is 38.

The square root of 8389721 is about 2896.5015104432. The cubic root of 8389721 is about 203.1963205489.

The spelling of 8389721 in words is "eight million, three hundred eighty-nine thousand, seven hundred twenty-one".