28208191 has 4 divisors (see below), whose sum is σ = 30772584. Its totient is φ = 25643800.

The previous prime is 28208183. The next prime is 28208197. The reversal of 28208191 is 19180282.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 28208191 - 2³ = 28208183 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28208197) 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, 1282180 + ... + 1282201.

It is an arithmetic number, because the mean of its divisors is an integer number (7693146).

Almost surely, 2^28208191 is an apocalyptic number.

28208191 is a deficient number, since it is larger than the sum of its proper divisors (2564393).

28208191 is a wasteful number, since it uses less digits than its factorization.

28208191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2564392.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 28208191 is about 5311.1383902135. The cubic root of 28208191 is about 304.4096472751.

It can be divided in two parts, 2820 and 8191, that added together give a palindrome (11011).

The spelling of 28208191 in words is "twenty-eight million, two hundred eight thousand, one hundred ninety-one".