28166321 has 4 divisors (see below), whose sum is σ = 29074944. Its totient is φ = 27257700.

The previous prime is 28166317. The next prime is 28166353. The reversal of 28166321 is 12366182.

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: 12366182 = 2 ⋅6183091.

It is a cyclic number.

It is not a de Polignac number, because 28166321 - 2² = 28166317 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28166371) 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 3 ways as a sum of consecutive naturals, for example, 454265 + ... + 454326.

It is an arithmetic number, because the mean of its divisors is an integer number (7268736).

Almost surely, 2^28166321 is an apocalyptic number.

It is an amenable number.

28166321 is a deficient number, since it is larger than the sum of its proper divisors (908623).

28166321 is an equidigital number, since it uses as much as digits as its factorization.

28166321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 908622.

The product of its digits is 3456, while the sum is 29.

The square root of 28166321 is about 5307.1952102782. The cubic root of 28166321 is about 304.2589588534.

The spelling of 28166321 in words is "twenty-eight million, one hundred sixty-six thousand, three hundred twenty-one".