21311123121 has 12 divisors (see below), whose sum is σ = 32402877520. Its totient is φ = 13459656600.

The previous prime is 21311123051. The next prime is 21311123147. The reversal of 21311123121 is 12132111312.

It is not a de Polignac number, because 21311123121 - 2²⁹ = 20774252209 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21311123094 and 21311123103.

It is not an unprimeable number, because it can be changed into a prime (21311123161) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 62313055 + ... + 62313396.

Almost surely, 2^21311123121 is an apocalyptic number.

It is an amenable number.

21311123121 is a deficient number, since it is larger than the sum of its proper divisors (11091754399).

21311123121 is a wasteful number, since it uses less digits than its factorization.

21311123121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124626476 (or 124626473 counting only the distinct ones).

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

Adding to 21311123121 its reverse (12132111312), we get a palindrome (33443234433).

The spelling of 21311123121 in words is "twenty-one billion, three hundred eleven million, one hundred twenty-three thousand, one hundred twenty-one".