28279221 has 8 divisors (see below), whose sum is σ = 37730784. Its totient is φ = 18840240.

The previous prime is 28279187. The next prime is 28279241. The reversal of 28279221 is 12297282.

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

It is not a de Polignac number, because 28279221 - 2⁷ = 28279093 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 (28279241) 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, 5491 + ... + 9311.

It is an arithmetic number, because the mean of its divisors is an integer number (4716348).

Almost surely, 2^28279221 is an apocalyptic number.

It is an amenable number.

28279221 is a deficient number, since it is larger than the sum of its proper divisors (9451563).

28279221 is a wasteful number, since it uses less digits than its factorization.

28279221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6291.

The product of its digits is 8064, while the sum is 33.

The square root of 28279221 is about 5317.8210763432. The cubic root of 28279221 is about 304.6649406624.

The spelling of 28279221 in words is "twenty-eight million, two hundred seventy-nine thousand, two hundred twenty-one".