28728091 has 8 divisors (see below), whose sum is σ = 33295104. Its totient is φ = 24276840.

The previous prime is 28728083. The next prime is 28728097. The reversal of 28728091 is 19082782.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28728091 - 2³ = 28728083 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28728091.

It is not an unprimeable number, because it can be changed into a prime (28728097) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28405 + ... + 29398.

It is an arithmetic number, because the mean of its divisors is an integer number (4161888).

Almost surely, 2^28728091 is an apocalyptic number.

28728091 is a deficient number, since it is larger than the sum of its proper divisors (4567013).

28728091 is an equidigital number, since it uses as much as digits as its factorization.

28728091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57881.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 28728091 is about 5359.8592332262. The cubic root of 28728091 is about 306.2684467023.

The spelling of 28728091 in words is "twenty-eight million, seven hundred twenty-eight thousand, ninety-one".