28720000009 has 2 divisors, whose sum is σ = 28720000010. Its totient is φ = 28720000008.

The previous prime is 28719999991. The next prime is 28720000013. The reversal of 28720000009 is 90000002782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26466409225 + 2253590784 = 162685^2 + 47472^2 .

It is a cyclic number.

It is not a de Polignac number, because 28720000009 - 2⁵ = 28719999977 is a prime.

It is not a weakly prime, because it can be changed into another prime (28720000079) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14360000004 + 14360000005.

It is an arithmetic number, because the mean of its divisors is an integer number (14360000005).

Almost surely, 2^28720000009 is an apocalyptic number.

It is an amenable number.

28720000009 is a deficient number, since it is larger than the sum of its proper divisors (1).

28720000009 is an equidigital number, since it uses as much as digits as its factorization.

28720000009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 28.

The spelling of 28720000009 in words is "twenty-eight billion, seven hundred twenty million, nine", and thus it is an aban number.