21111312321 has 24 divisors (see below), whose sum is σ = 33440509440. Its totient is φ = 12727735200.

The previous prime is 21111312301. The next prime is 21111312347. The reversal of 21111312321 is 12321311112.

21111312321 is a `hidden beast` number, since 21 + 1 + 11 + 312 + 321 = 666.

It is not a de Polignac number, because 21111312321 - 2¹¹ = 21111310273 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21111312294 and 21111312303.

It is not an unprimeable number, because it can be changed into a prime (21111312301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 539326 + ... + 577143.

It is an arithmetic number, because the mean of its divisors is an integer number (1393354560).

Almost surely, 2^21111312321 is an apocalyptic number.

It is an amenable number.

21111312321 is a deficient number, since it is larger than the sum of its proper divisors (12329197119).

21111312321 is a wasteful number, since it uses less digits than its factorization.

21111312321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1116677 (or 1116674 counting only the distinct ones).

The product of its digits is 72, while the sum is 18.

Adding to 21111312321 its reverse (12321311112), we get a palindrome (33432623433).

The spelling of 21111312321 in words is "twenty-one billion, one hundred eleven million, three hundred twelve thousand, three hundred twenty-one".