28901209 has 4 divisors (see below), whose sum is σ = 29391120. Its totient is φ = 28411300.

The previous prime is 28901177. The next prime is 28901221. The reversal of 28901209 is 90210982.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28901209 - 2⁵ = 28901177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28901809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 244867 + ... + 244984.

It is an arithmetic number, because the mean of its divisors is an integer number (7347780).

Almost surely, 2^28901209 is an apocalyptic number.

It is an amenable number.

28901209 is a deficient number, since it is larger than the sum of its proper divisors (489911).

28901209 is an equidigital number, since it uses as much as digits as its factorization.

28901209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 489910.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 28901209 is about 5375.9844679835. The cubic root of 28901209 is about 306.8824152607.

The spelling of 28901209 in words is "twenty-eight million, nine hundred one thousand, two hundred nine".