28678221 has 24 divisors (see below), whose sum is σ = 48668256. Its totient is φ = 16043040.

The previous prime is 28678213. The next prime is 28678253. The reversal of 28678221 is 12287682.

It is a happy number.

It is not a de Polignac number, because 28678221 - 2³ = 28678213 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28678271) 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 23 ways as a sum of consecutive naturals, for example, 9855 + ... + 12428.

It is an arithmetic number, because the mean of its divisors is an integer number (2027844).

Almost surely, 2^28678221 is an apocalyptic number.

It is an amenable number.

28678221 is a deficient number, since it is larger than the sum of its proper divisors (19990035).

28678221 is a wasteful number, since it uses less digits than its factorization.

28678221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22313 (or 22310 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 28678221 is about 5355.2050380914. The cubic root of 28678221 is about 306.0911237010.

The spelling of 28678221 in words is "twenty-eight million, six hundred seventy-eight thousand, two hundred twenty-one".