28921009 has 8 divisors (see below), whose sum is σ = 31187520. Its totient is φ = 26660496.

The previous prime is 28921007. The next prime is 28921037. The reversal of 28921009 is 90012982.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28921009 - 2¹ = 28921007 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28921007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17772 + ... + 19330.

It is an arithmetic number, because the mean of its divisors is an integer number (3898440).

Almost surely, 2^28921009 is an apocalyptic number.

It is an amenable number.

28921009 is a deficient number, since it is larger than the sum of its proper divisors (2266511).

28921009 is a wasteful number, since it uses less digits than its factorization.

28921009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2999.

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

The square root of 28921009 is about 5377.8256758657. The cubic root of 28921009 is about 306.9524802045.

The spelling of 28921009 in words is "twenty-eight million, nine hundred twenty-one thousand, nine".