28198091 has 4 divisors (see below), whose sum is σ = 28254000. Its totient is φ = 28142184.

The previous prime is 28198081. The next prime is 28198097. The reversal of 28198091 is 19089182.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28198091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28198097) 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, 27191 + ... + 28208.

It is an arithmetic number, because the mean of its divisors is an integer number (7063500).

Almost surely, 2^28198091 is an apocalyptic number.

28198091 is a deficient number, since it is larger than the sum of its proper divisors (55909).

28198091 is an equidigital number, since it uses as much as digits as its factorization.

28198091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55908.

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 28198091 is about 5310.1874731501. The cubic root of 28198091 is about 304.3733114408.

The spelling of 28198091 in words is "twenty-eight million, one hundred ninety-eight thousand, ninety-one".