8210721 has 8 divisors (see below), whose sum is σ = 11202400. Its totient is φ = 5346432.

The previous prime is 8210681. The next prime is 8210723. The reversal of 8210721 is 1270128.

8210721 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 8210721 - 2¹⁴ = 8194337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8210723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31696 + ... + 31953.

It is an arithmetic number, because the mean of its divisors is an integer number (1400300).

Almost surely, 2^8210721 is an apocalyptic number.

It is an amenable number.

8210721 is a deficient number, since it is larger than the sum of its proper divisors (2991679).

8210721 is a wasteful number, since it uses less digits than its factorization.

8210721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63695.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 8210721 is about 2865.4355689842. The cubic root of 8210721 is about 201.7408122354.

Adding to 8210721 its reverse (1270128), we get a palindrome (9480849).

It can be divided in two parts, 82107 and 21, that added together give a palindrome (82128).

The spelling of 8210721 in words is "eight million, two hundred ten thousand, seven hundred twenty-one".