21111001121 has 4 divisors (see below), whose sum is σ = 24126858432. Its totient is φ = 18095143812.

The previous prime is 21111001117. The next prime is 21111001127. The reversal of 21111001121 is 12110011112.

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 21111001121 - 2² = 21111001117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111001127) 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, 1507928645 + ... + 1507928658.

It is an arithmetic number, because the mean of its divisors is an integer number (6031714608).

Almost surely, 2^21111001121 is an apocalyptic number.

It is an amenable number.

21111001121 is a deficient number, since it is larger than the sum of its proper divisors (3015857311).

21111001121 is an equidigital number, since it uses as much as digits as its factorization.

21111001121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3015857310.

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 21111001121 its reverse (12110011112), we get a palindrome (33221012233).

Subtracting from 21111001121 its reverse (12110011112), we obtain a palindrome (9000990009).

The spelling of 21111001121 in words is "twenty-one billion, one hundred eleven million, one thousand, one hundred twenty-one".