8390721 has 8 divisors (see below), whose sum is σ = 11219584. Its totient is φ = 5577840.

The previous prime is 8390717. The next prime is 8390729. The reversal of 8390721 is 1270938.

It is a happy number.

8390721 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 not a de Polignac number, because 8390721 - 2² = 8390717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8390729) 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, 2710 + ... + 4911.

It is an arithmetic number, because the mean of its divisors is an integer number (1402448).

Almost surely, 2^8390721 is an apocalyptic number.

It is an amenable number.

8390721 is a deficient number, since it is larger than the sum of its proper divisors (2828863).

8390721 is a wasteful number, since it uses less digits than its factorization.

8390721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7991.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 8390721 is about 2896.6741273398. The cubic root of 8390721 is about 203.2043934534.

The spelling of 8390721 in words is "eight million, three hundred ninety thousand, seven hundred twenty-one".