28748509 has 2 divisors, whose sum is σ = 28748510. Its totient is φ = 28748508.

The previous prime is 28748477. The next prime is 28748521. The reversal of 28748509 is 90584782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15824484 + 12924025 = 3978^2 + 3595^2 .

It is a cyclic number.

It is not a de Polignac number, because 28748509 - 2⁵ = 28748477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28748579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14374254 + 14374255.

It is an arithmetic number, because the mean of its divisors is an integer number (14374255).

Almost surely, 2^28748509 is an apocalyptic number.

It is an amenable number.

28748509 is a deficient number, since it is larger than the sum of its proper divisors (1).

28748509 is an equidigital number, since it uses as much as digits as its factorization.

28748509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 161280, while the sum is 43.

The square root of 28748509 is about 5361.7636091122. The cubic root of 28748509 is about 306.3409878750.

The spelling of 28748509 in words is "twenty-eight million, seven hundred forty-eight thousand, five hundred nine".