21122012121 has 16 divisors (see below), whose sum is σ = 32191334784. Its totient is φ = 12067691904.

The previous prime is 21122012053. The next prime is 21122012123. The reversal of 21122012121 is 12121022112.

It is not a de Polignac number, because 21122012121 - 2¹⁵ = 21121979353 is a prime.

It is a super-2 number, since 2×21122012121² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21122012121.

It is not an unprimeable number, because it can be changed into a prime (21122012123) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48165 + ... + 211101.

It is an arithmetic number, because the mean of its divisors is an integer number (2011958424).

Almost surely, 2^21122012121 is an apocalyptic number.

21122012121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21122012121 is a deficient number, since it is larger than the sum of its proper divisors (11069322663).

21122012121 is a wasteful number, since it uses less digits than its factorization.

21122012121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169120.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21122012121 its reverse (12121022112), we get a palindrome (33243034233).

Subtracting from 21122012121 its reverse (12121022112), we obtain a palindrome (9000990009).

The spelling of 21122012121 in words is "twenty-one billion, one hundred twenty-two million, twelve thousand, one hundred twenty-one".