21010112121 has 16 divisors (see below), whose sum is σ = 28437231168. Its totient is φ = 13794950400.

The previous prime is 21010112089. The next prime is 21010112159. The reversal of 21010112121 is 12121101012.

It is not a de Polignac number, because 21010112121 - 2⁵ = 21010112089 is a prime.

It is a super-2 number, since 2×21010112121² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21010112097 and 21010112106.

It is not an unprimeable number, because it can be changed into a prime (21010112191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1738861 + ... + 1750901.

It is an arithmetic number, because the mean of its divisors is an integer number (1777326948).

Almost surely, 2^21010112121 is an apocalyptic number.

It is an amenable number.

21010112121 is a deficient number, since it is larger than the sum of its proper divisors (7427119047).

21010112121 is a wasteful number, since it uses less digits than its factorization.

21010112121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20792.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21010112121 its reverse (12121101012), we get a palindrome (33131213133).

It can be divided in two parts, 210101 and 12121, that added together give a palindrome (222222).

The spelling of 21010112121 in words is "twenty-one billion, ten million, one hundred twelve thousand, one hundred twenty-one".