8644721 has 4 divisors (see below), whose sum is σ = 9153252. Its totient is φ = 8136192.

The previous prime is 8644703. The next prime is 8644723. The reversal of 8644721 is 1274468.

8644721 is nontrivially palindromic in base 6.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8065600 + 579121 = 2840^2 + 761^2 .

It is a cyclic number.

It is not a de Polignac number, because 8644721 - 2¹⁰ = 8643697 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (8644723) 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 3 ways as a sum of consecutive naturals, for example, 254240 + ... + 254273.

It is an arithmetic number, because the mean of its divisors is an integer number (2288313).

Almost surely, 2^8644721 is an apocalyptic number.

It is an amenable number.

8644721 is a deficient number, since it is larger than the sum of its proper divisors (508531).

8644721 is a wasteful number, since it uses less digits than its factorization.

8644721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 508530.

The product of its digits is 10752, while the sum is 32.

The square root of 8644721 is about 2940.1906400776. The cubic root of 8644721 is about 205.2344808537.

It can be divided in two parts, 86447 and 21, that added together give a palindrome (86468).

The spelling of 8644721 in words is "eight million, six hundred forty-four thousand, seven hundred twenty-one".