28267891 has 4 divisors (see below), whose sum is σ = 28608552. Its totient is φ = 27927232.

The previous prime is 28267867. The next prime is 28267907. The reversal of 28267891 is 19876282.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19876282 = 2 ⋅9938141.

It is a cyclic number.

It is not a de Polignac number, because 28267891 - 2¹¹ = 28265843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28267831) 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, 170206 + ... + 170371.

It is an arithmetic number, because the mean of its divisors is an integer number (7152138).

Almost surely, 2^28267891 is an apocalyptic number.

28267891 is a deficient number, since it is larger than the sum of its proper divisors (340661).

28267891 is an equidigital number, since it uses as much as digits as its factorization.

28267891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340660.

The product of its digits is 96768, while the sum is 43.

The square root of 28267891 is about 5316.7556836853. The cubic root of 28267891 is about 304.6242474756.

The spelling of 28267891 in words is "twenty-eight million, two hundred sixty-seven thousand, eight hundred ninety-one".