28666191 has 4 divisors (see below), whose sum is σ = 38221592. Its totient is φ = 19110792.

The previous prime is 28666189. The next prime is 28666201. The reversal of 28666191 is 19166682.

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

It is not a de Polignac number, because 28666191 - 2¹ = 28666189 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 (28666091) 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, 4777696 + ... + 4777701.

It is an arithmetic number, because the mean of its divisors is an integer number (9555398).

Almost surely, 2^28666191 is an apocalyptic number.

28666191 is a deficient number, since it is larger than the sum of its proper divisors (9555401).

28666191 is an equidigital number, since it uses as much as digits as its factorization.

28666191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9555400.

The product of its digits is 31104, while the sum is 39.

The square root of 28666191 is about 5354.0817139823. The cubic root of 28666191 is about 306.0483178005.

The spelling of 28666191 in words is "twenty-eight million, six hundred sixty-six thousand, one hundred ninety-one".