28904209 has 2 divisors, whose sum is σ = 28904210. Its totient is φ = 28904208.

The previous prime is 28904207. The next prime is 28904219. The reversal of 28904209 is 90240982.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14653584 + 14250625 = 3828^2 + 3775^2 .

It is a cyclic number.

It is not a de Polignac number, because 28904209 - 2¹ = 28904207 is a prime.

Together with 28904207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (28904203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14452104 + 14452105.

It is an arithmetic number, because the mean of its divisors is an integer number (14452105).

Almost surely, 2^28904209 is an apocalyptic number.

It is an amenable number.

28904209 is a deficient number, since it is larger than the sum of its proper divisors (1).

28904209 is an equidigital number, since it uses as much as digits as its factorization.

28904209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 28904209 is about 5376.2634794065. The cubic root of 28904209 is about 306.8930332178.

The spelling of 28904209 in words is "twenty-eight million, nine hundred four thousand, two hundred nine".