21868585 has 4 divisors (see below), whose sum is σ = 26242308. Its totient is φ = 17494864.

The previous prime is 21868573. The next prime is 21868589. The reversal of 21868585 is 58586812.

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 2972176 + 18896409 = 1724^2 + 4347^2 .

It is a cyclic number.

It is not a de Polignac number, because 21868585 - 2¹⁵ = 21835817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21868589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2186854 + ... + 2186863.

It is an arithmetic number, because the mean of its divisors is an integer number (6560577).

Almost surely, 2^21868585 is an apocalyptic number.

It is an amenable number.

21868585 is a deficient number, since it is larger than the sum of its proper divisors (4373723).

21868585 is an equidigital number, since it uses as much as digits as its factorization.

21868585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4373722.

The product of its digits is 153600, while the sum is 43.

The square root of 21868585 is about 4676.3858908349. The cubic root of 21868585 is about 279.6448942206.

The spelling of 21868585 in words is "twenty-one million, eight hundred sixty-eight thousand, five hundred eighty-five".