8728921 has 2 divisors, whose sum is σ = 8728922. Its totient is φ = 8728920.

The previous prime is 8728903. The next prime is 8728927. The reversal of 8728921 is 1298278.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7485696 + 1243225 = 2736^2 + 1115^2 .

It is a cyclic number.

It is not a de Polignac number, because 8728921 - 2¹¹ = 8726873 is a prime.

It is a nialpdrome in base 15.

It is not a weakly prime, because it can be changed into another prime (8728927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4364460 + 4364461.

It is an arithmetic number, because the mean of its divisors is an integer number (4364461).

Almost surely, 2^8728921 is an apocalyptic number.

It is an amenable number.

8728921 is a deficient number, since it is larger than the sum of its proper divisors (1).

8728921 is an equidigital number, since it uses as much as digits as its factorization.

8728921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 37.

The square root of 8728921 is about 2954.4747418111. The cubic root of 8728921 is about 205.8986603698.

The spelling of 8728921 in words is "eight million, seven hundred twenty-eight thousand, nine hundred twenty-one".