8721385609 has 2 divisors, whose sum is σ = 8721385610. Its totient is φ = 8721385608.

The previous prime is 8721385597. The next prime is 8721385637. The reversal of 8721385609 is 9065831278.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6273115209 + 2448270400 = 79203^2 + 49480^2 .

It is a cyclic number.

It is not a de Polignac number, because 8721385609 - 2¹⁵ = 8721352841 is a prime.

It is not a weakly prime, because it can be changed into another prime (8721385669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4360692804 + 4360692805.

It is an arithmetic number, because the mean of its divisors is an integer number (4360692805).

Almost surely, 2^8721385609 is an apocalyptic number.

It is an amenable number.

8721385609 is a deficient number, since it is larger than the sum of its proper divisors (1).

8721385609 is an equidigital number, since it uses as much as digits as its factorization.

8721385609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 725760, while the sum is 49.

The square root of 8721385609 is about 93388.3590657851. The cubic root of 8721385609 is about 2058.3939479397.

The spelling of 8721385609 in words is "eight billion, seven hundred twenty-one million, three hundred eighty-five thousand, six hundred nine".