28663221 has 8 divisors (see below), whose sum is σ = 39879360. Its totient is φ = 18277952.

The previous prime is 28663213. The next prime is 28663237. The reversal of 28663221 is 12236682.

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 28663221 - 2³ = 28663213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28663121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 207636 + ... + 207773.

It is an arithmetic number, because the mean of its divisors is an integer number (4984920).

Almost surely, 2^28663221 is an apocalyptic number.

It is an amenable number.

28663221 is a deficient number, since it is larger than the sum of its proper divisors (11216139).

28663221 is a wasteful number, since it uses less digits than its factorization.

28663221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415435.

The product of its digits is 6912, while the sum is 30.

The square root of 28663221 is about 5353.8043483116. The cubic root of 28663221 is about 306.0377479171.

The spelling of 28663221 in words is "twenty-eight million, six hundred sixty-three thousand, two hundred twenty-one".