21131304321 has 16 divisors (see below), whose sum is σ = 29164427264. Its totient is φ = 13598855424.

The previous prime is 21131304281. The next prime is 21131304323. The reversal of 21131304321 is 12340313112.

It is a de Polignac number, because none of the positive numbers 2^k-21131304321 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 (21131304323) 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, 735400 + ... + 763593.

It is an arithmetic number, because the mean of its divisors is an integer number (1822776704).

Almost surely, 2^21131304321 is an apocalyptic number.

It is an amenable number.

21131304321 is a deficient number, since it is larger than the sum of its proper divisors (8033122943).

21131304321 is a wasteful number, since it uses less digits than its factorization.

21131304321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1499160.

The product of its (nonzero) digits is 432, while the sum is 21.

Adding to 21131304321 its reverse (12340313112), we get a palindrome (33471617433).

The spelling of 21131304321 in words is "twenty-one billion, one hundred thirty-one million, three hundred four thousand, three hundred twenty-one".