21201211121 has 4 divisors (see below), whose sum is σ = 21204014592. Its totient is φ = 21198407652.

The previous prime is 21201211111. The next prime is 21201211133. The reversal of 21201211121 is 12111210212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21201211121 - 2²² = 21197016817 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201211096 and 21201211105.

It is not an unprimeable number, because it can be changed into a prime (21201211111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1390361 + ... + 1405526.

It is an arithmetic number, because the mean of its divisors is an integer number (5301003648).

Almost surely, 2^21201211121 is an apocalyptic number.

It is an amenable number.

21201211121 is a deficient number, since it is larger than the sum of its proper divisors (2803471).

21201211121 is an equidigital number, since it uses as much as digits as its factorization.

21201211121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2803470.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21201211121 its reverse (12111210212), we get a palindrome (33312421333).

Subtracting from 21201211121 its reverse (12111210212), we obtain a palindrome (9090000909).

The spelling of 21201211121 in words is "twenty-one billion, two hundred one million, two hundred eleven thousand, one hundred twenty-one".