28809000721 has 2 divisors, whose sum is σ = 28809000722. Its totient is φ = 28809000720.

The previous prime is 28809000659. The next prime is 28809000739. The reversal of 28809000721 is 12700090882.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16979393025 + 11829607696 = 130305^2 + 108764^2 .

It is a cyclic number.

It is not a de Polignac number, because 28809000721 - 2⁷ = 28809000593 is a prime.

It is not a weakly prime, because it can be changed into another prime (28809000821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14404500360 + 14404500361.

It is an arithmetic number, because the mean of its divisors is an integer number (14404500361).

Almost surely, 2^28809000721 is an apocalyptic number.

It is an amenable number.

28809000721 is a deficient number, since it is larger than the sum of its proper divisors (1).

28809000721 is an equidigital number, since it uses as much as digits as its factorization.

28809000721 is an evil number, because the sum of its binary digits is even.

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

The spelling of 28809000721 in words is "twenty-eight billion, eight hundred nine million, seven hundred twenty-one", and thus it is an aban number.