28868821 has 4 divisors (see below), whose sum is σ = 28898944. Its totient is φ = 28838700.

The previous prime is 28868803. The next prime is 28868831. The reversal of 28868821 is 12886882.

It is a happy number.

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 28868821 - 2¹⁷ = 28737749 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28868831) 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 in 3 ways as a sum of consecutive naturals, for example, 13575 + ... + 15556.

It is an arithmetic number, because the mean of its divisors is an integer number (7224736).

Almost surely, 2^28868821 is an apocalyptic number.

It is an amenable number.

28868821 is a deficient number, since it is larger than the sum of its proper divisors (30123).

28868821 is an equidigital number, since it uses as much as digits as its factorization.

28868821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30122.

The product of its digits is 98304, while the sum is 43.

The square root of 28868821 is about 5372.9713380959. The cubic root of 28868821 is about 306.7677369810.

The spelling of 28868821 in words is "twenty-eight million, eight hundred sixty-eight thousand, eight hundred twenty-one".