28591813 has 4 divisors (see below), whose sum is σ = 29076480. Its totient is φ = 28107148.

The previous prime is 28591799. The next prime is 28591847. The reversal of 28591813 is 31819582.

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 28591813 - 2⁹ = 28591301 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 (28591853) 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, 242245 + ... + 242362.

It is an arithmetic number, because the mean of its divisors is an integer number (7269120).

Almost surely, 2^28591813 is an apocalyptic number.

It is an amenable number.

28591813 is a deficient number, since it is larger than the sum of its proper divisors (484667).

28591813 is an equidigital number, since it uses as much as digits as its factorization.

28591813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484666.

The product of its digits is 17280, while the sum is 37.

The square root of 28591813 is about 5347.1312869613. The cubic root of 28591813 is about 305.7833950607.

The spelling of 28591813 in words is "twenty-eight million, five hundred ninety-one thousand, eight hundred thirteen".