21216363431513 has 4 divisors (see below), whose sum is σ = 21219834133428. Its totient is φ = 21212892729600.

The previous prime is 21216363431479. The next prime is 21216363431539. The reversal of 21216363431513 is 31513436361212.

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 15498181653529 + 5718181777984 = 3936773^2 + 2391272^2 .

It is a cyclic number.

It is not a de Polignac number, because 21216363431513 - 2²⁰ = 21216362382937 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21216363437513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1735341788 + ... + 1735354013.

It is an arithmetic number, because the mean of its divisors is an integer number (5304958533357).

Almost surely, 2^{21216363431513} is an apocalyptic number.

It is an amenable number.

21216363431513 is a deficient number, since it is larger than the sum of its proper divisors (3470701915).

21216363431513 is an equidigital number, since it uses as much as digits as its factorization.

21216363431513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3470701914.

The product of its digits is 233280, while the sum is 41.

Adding to 21216363431513 its reverse (31513436361212), we get a palindrome (52729799792725).

The spelling of 21216363431513 in words is "twenty-one trillion, two hundred sixteen billion, three hundred sixty-three million, four hundred thirty-one thousand, five hundred thirteen".