21321285 has 16 divisors (see below), whose sum is σ = 34499520. Its totient is φ = 11242880.

The previous prime is 21321283. The next prime is 21321301. The reversal of 21321285 is 58212312.

It is not a de Polignac number, because 21321285 - 2¹ = 21321283 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321283) 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 15 ways as a sum of consecutive naturals, for example, 6651 + ... + 9320.

It is an arithmetic number, because the mean of its divisors is an integer number (2156220).

Almost surely, 2^21321285 is an apocalyptic number.

It is an amenable number.

21321285 is a deficient number, since it is larger than the sum of its proper divisors (13178235).

21321285 is a wasteful number, since it uses less digits than its factorization.

21321285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16068.

The product of its digits is 960, while the sum is 24.

The square root of 21321285 is about 4617.4976989707. The cubic root of 21321285 is about 277.2922883596.

Adding to 21321285 its reverse (58212312), we get a palindrome (79533597).

The spelling of 21321285 in words is "twenty-one million, three hundred twenty-one thousand, two hundred eighty-five".