28928881 has 4 divisors (see below), whose sum is σ = 28949872. Its totient is φ = 28907892.

The previous prime is 28928843. The next prime is 28928891. The reversal of 28928881 is 18882982.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18882982 = 2 ⋅9441491.

It is a cyclic number.

It is not a de Polignac number, because 28928881 - 2¹⁷ = 28797809 is a prime.

It is a super-2 number, since 2×28928881² = 1673760311824322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28928891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8271 + ... + 11236.

It is an arithmetic number, because the mean of its divisors is an integer number (7237468).

Almost surely, 2^28928881 is an apocalyptic number.

It is an amenable number.

28928881 is a deficient number, since it is larger than the sum of its proper divisors (20991).

28928881 is a wasteful number, since it uses less digits than its factorization.

28928881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20990.

The product of its digits is 147456, while the sum is 46.

The square root of 28928881 is about 5378.5575203766. The cubic root of 28928881 is about 306.9803274432.

The spelling of 28928881 in words is "twenty-eight million, nine hundred twenty-eight thousand, eight hundred eighty-one".