28740991 has 4 divisors (see below), whose sum is σ = 29087352. Its totient is φ = 28394632.

The previous prime is 28740979. The next prime is 28741039. The reversal of 28740991 is 19904782.

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

It is not a de Polignac number, because 28740991 - 2¹⁹ = 28216703 is a prime.

It is a Smith number, since the sum of its digits (40) 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 (28740091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 173056 + ... + 173221.

It is an arithmetic number, because the mean of its divisors is an integer number (7271838).

Almost surely, 2^28740991 is an apocalyptic number.

28740991 is a deficient number, since it is larger than the sum of its proper divisors (346361).

28740991 is an equidigital number, since it uses as much as digits as its factorization.

28740991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 346360.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 28740991 is about 5361.0624879775. The cubic root of 28740991 is about 306.3142818832.

The spelling of 28740991 in words is "twenty-eight million, seven hundred forty thousand, nine hundred ninety-one".