28091099 has 4 divisors (see below), whose sum is σ = 28112136. Its totient is φ = 28070064.

The previous prime is 28091093. The next prime is 28091117. The reversal of 28091099 is 99019082.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99019082 = 2 ⋅49509541.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28091099 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28091093) 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, 8369 + ... + 11234.

It is an arithmetic number, because the mean of its divisors is an integer number (7028034).

Almost surely, 2^28091099 is an apocalyptic number.

28091099 is a deficient number, since it is larger than the sum of its proper divisors (21037).

28091099 is a wasteful number, since it uses less digits than its factorization.

28091099 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21036.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 28091099 is about 5300.1036782312. The cubic root of 28091099 is about 303.9878623674.

The spelling of 28091099 in words is "twenty-eight million, ninety-one thousand, ninety-nine".