8291721 has 8 divisors (see below), whose sum is σ = 11069344. Its totient is φ = 5520960.

The previous prime is 8291713. The next prime is 8291729. The reversal of 8291721 is 1271928.

8291721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (8291713) and next prime (8291729).

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

It is not a de Polignac number, because 8291721 - 2³ = 8291713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8291729) 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, 2826 + ... + 4956.

It is an arithmetic number, because the mean of its divisors is an integer number (1383668).

Almost surely, 2^8291721 is an apocalyptic number.

It is an amenable number.

8291721 is a deficient number, since it is larger than the sum of its proper divisors (2777623).

8291721 is a wasteful number, since it uses less digits than its factorization.

8291721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3431.

The product of its digits is 2016, while the sum is 30.

The square root of 8291721 is about 2879.5348582714. The cubic root of 8291721 is about 202.4020437675.

The spelling of 8291721 in words is "eight million, two hundred ninety-one thousand, seven hundred twenty-one".