8628721 has 4 divisors (see below), whose sum is σ = 8678772. Its totient is φ = 8578672.

The previous prime is 8628709. The next prime is 8628727. The reversal of 8628721 is 1278268.

8628721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 3629025 + 4999696 = 1905^2 + 2236^2 .

It is a cyclic number.

It is not a de Polignac number, because 8628721 - 2¹³ = 8620529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8628727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24766 + ... + 25111.

It is an arithmetic number, because the mean of its divisors is an integer number (2169693).

Almost surely, 2^8628721 is an apocalyptic number.

It is an amenable number.

8628721 is a deficient number, since it is larger than the sum of its proper divisors (50051).

8628721 is a wasteful number, since it uses less digits than its factorization.

8628721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50050.

The product of its digits is 10752, while the sum is 34.

The square root of 8628721 is about 2937.4684679159. The cubic root of 8628721 is about 205.1077838911.

The spelling of 8628721 in words is "eight million, six hundred twenty-eight thousand, seven hundred twenty-one".