28371891 has 4 divisors (see below), whose sum is σ = 37829192. Its totient is φ = 18914592.

The previous prime is 28371881. The next prime is 28371899. The reversal of 28371891 is 19817382.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 28371891 - 2¹¹ = 28369843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28371899) 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, 4728646 + ... + 4728651.

It is an arithmetic number, because the mean of its divisors is an integer number (9457298).

Almost surely, 2^28371891 is an apocalyptic number.

28371891 is a deficient number, since it is larger than the sum of its proper divisors (9457301).

28371891 is an equidigital number, since it uses as much as digits as its factorization.

28371891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9457300.

The product of its digits is 24192, while the sum is 39.

The square root of 28371891 is about 5326.5271049719. The cubic root of 28371891 is about 304.9973698600.

The spelling of 28371891 in words is "twenty-eight million, three hundred seventy-one thousand, eight hundred ninety-one".