21111210222121 has 24 divisors (see below), whose sum is σ = 21676046895360. Its totient is φ = 20557189342656.

The previous prime is 21111210222073. The next prime is 21111210222127. The reversal of 21111210222121 is 12122201211112.

It is a happy number.

It is not a de Polignac number, because 21111210222121 - 2²⁷ = 21111076004393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111210222127) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 784002960 + ... + 784029886.

It is an arithmetic number, because the mean of its divisors is an integer number (903168620640).

Almost surely, 2^{21111210222121} is an apocalyptic number.

It is an amenable number.

21111210222121 is a deficient number, since it is larger than the sum of its proper divisors (564836673239).

21111210222121 is an equidigital number, since it uses as much as digits as its factorization.

21111210222121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28725 (or 28642 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21111210222121 its reverse (12122201211112), we get a palindrome (33233411433233).

The spelling of 21111210222121 in words is "twenty-one trillion, one hundred eleven billion, two hundred ten million, two hundred twenty-two thousand, one hundred twenty-one".