28367221 has 4 divisors (see below), whose sum is σ = 28382112. Its totient is φ = 28352332.

The previous prime is 28367219. The next prime is 28367233. The reversal of 28367221 is 12276382.

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: 12276382 = 2 ⋅6138191.

It is a cyclic number.

It is not a de Polignac number, because 28367221 - 2¹ = 28367219 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28367281) 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, 4081 + ... + 8566.

It is an arithmetic number, because the mean of its divisors is an integer number (7095528).

Almost surely, 2^28367221 is an apocalyptic number.

It is an amenable number.

28367221 is a deficient number, since it is larger than the sum of its proper divisors (14891).

28367221 is a wasteful number, since it uses less digits than its factorization.

28367221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14890.

The product of its digits is 8064, while the sum is 31.

The square root of 28367221 is about 5326.0887149953. The cubic root of 28367221 is about 304.9806348002.

The spelling of 28367221 in words is "twenty-eight million, three hundred sixty-seven thousand, two hundred twenty-one".