21318085 has 12 divisors (see below), whose sum is σ = 27176868. Its totient is φ = 16050176.

The previous prime is 21318047. The next prime is 21318091. The reversal of 21318085 is 58081312.

It can be written as a sum of positive squares in 6 ways, for example, as 1014049 + 20304036 = 1007^2 + 4506^2 .

It is not a de Polignac number, because 21318085 - 2¹¹ = 21316037 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 5932 + ... + 8821.

It is an arithmetic number, because the mean of its divisors is an integer number (2264739).

Almost surely, 2^21318085 is an apocalyptic number.

It is an amenable number.

21318085 is a deficient number, since it is larger than the sum of its proper divisors (5858783).

21318085 is a wasteful number, since it uses less digits than its factorization.

21318085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14792 (or 14775 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 21318085 is about 4617.1511779451. The cubic root of 21318085 is about 277.2784152164.

Adding to 21318085 its reverse (58081312), we get a palindrome (79399397).

The spelling of 21318085 in words is "twenty-one million, three hundred eighteen thousand, eighty-five".