21236313 has 16 divisors (see below), whose sum is σ = 32818176. Its totient is φ = 11963280.

The previous prime is 21236311. The next prime is 21236317. The reversal of 21236313 is 31363212.

It is not a de Polignac number, because 21236313 - 2¹ = 21236311 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21236313.

It is not an unprimeable number, because it can be changed into a prime (21236311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5631 + ... + 8612.

It is an arithmetic number, because the mean of its divisors is an integer number (2051136).

Almost surely, 2^21236313 is an apocalyptic number.

It is an amenable number.

21236313 is a deficient number, since it is larger than the sum of its proper divisors (11581863).

21236313 is a wasteful number, since it uses less digits than its factorization.

21236313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14324.

The product of its digits is 648, while the sum is 21.

The square root of 21236313 is about 4608.2874259317. The cubic root of 21236313 is about 276.9234323773.

Adding to 21236313 its reverse (31363212), we get a palindrome (52599525).

The spelling of 21236313 in words is "twenty-one million, two hundred thirty-six thousand, three hundred thirteen".