21118585 has 4 divisors (see below), whose sum is σ = 25342308. Its totient is φ = 16894864.

The previous prime is 21118579. The next prime is 21118613. The reversal of 21118585 is 58581112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10601536 + 10517049 = 3256^2 + 3243^2 .

It is a cyclic number.

It is not a de Polignac number, because 21118585 - 2⁵ = 21118553 is a prime.

It is a Smith number, since the sum of its digits (31) 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 an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2111854 + ... + 2111863.

It is an arithmetic number, because the mean of its divisors is an integer number (6335577).

Almost surely, 2^21118585 is an apocalyptic number.

It is an amenable number.

21118585 is a deficient number, since it is larger than the sum of its proper divisors (4223723).

21118585 is an equidigital number, since it uses as much as digits as its factorization.

21118585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4223722.

The product of its digits is 3200, while the sum is 31.

The square root of 21118585 is about 4595.4961647248. The cubic root of 21118585 is about 276.4107559257.

Adding to 21118585 its reverse (58581112), we get a palindrome (79699697).

The spelling of 21118585 in words is "twenty-one million, one hundred eighteen thousand, five hundred eighty-five".