28991189 has 4 divisors (see below), whose sum is σ = 29128800. Its totient is φ = 28853580.

The previous prime is 28991173. The next prime is 28991191. The reversal of 28991189 is 98119982.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28991189 - 2⁴ = 28991173 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28991129) 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, 68489 + ... + 68910.

It is an arithmetic number, because the mean of its divisors is an integer number (7282200).

Almost surely, 2^28991189 is an apocalyptic number.

It is an amenable number.

28991189 is a deficient number, since it is larger than the sum of its proper divisors (137611).

28991189 is a wasteful number, since it uses less digits than its factorization.

28991189 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137610.

The product of its digits is 93312, while the sum is 47.

The square root of 28991189 is about 5384.3466641738. The cubic root of 28991189 is about 307.2005642633.

The spelling of 28991189 in words is "twenty-eight million, nine hundred ninety-one thousand, one hundred eighty-nine".