21111210121 has 8 divisors (see below), whose sum is σ = 21202781600. Its totient is φ = 21019806720.

The previous prime is 21111210119. The next prime is 21111210161. The reversal of 21111210121 is 12101211112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21111210121 - 2¹ = 21111210119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111210161) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 213070 + ... + 296008.

It is an arithmetic number, because the mean of its divisors is an integer number (2650347700).

Almost surely, 2^21111210121 is an apocalyptic number.

It is an amenable number.

21111210121 is a deficient number, since it is larger than the sum of its proper divisors (91571479).

21111210121 is an equidigital number, since it uses as much as digits as its factorization.

21111210121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84039.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21111210121 its reverse (12101211112), we get a palindrome (33212421233).

Subtracting from 21111210121 its reverse (12101211112), we obtain a palindrome (9009999009).

The spelling of 21111210121 in words is "twenty-one billion, one hundred eleven million, two hundred ten thousand, one hundred twenty-one".