221212112121 has 288 divisors, whose sum is σ = 449898209280. Its totient is φ = 101613657600.

The previous prime is 221212112113. The next prime is 221212112153. The reversal of 221212112121 is 121211212122.

221212112121 is a `hidden beast` number, since 221 + 21 + 211 + 212 + 1 = 666.

221212112121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 221212112121 - 2³ = 221212112113 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221212112094 and 221212112103.

It is not an unprimeable number, because it can be changed into a prime (221212112521) 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 287 ways as a sum of consecutive naturals, for example, 307666000 + ... + 307666718.

It is an arithmetic number, because the mean of its divisors is an integer number (1562146560).

Almost surely, 2^221212112121 is an apocalyptic number.

221212112121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

221212112121 is an abundant number, since it is smaller than the sum of its proper divisors (228686097159).

221212112121 is a wasteful number, since it uses less digits than its factorization.

221212112121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 877 (or 861 counting only the distinct ones).

The product of its digits is 64, while the sum is 18.

Adding to 221212112121 its reverse (121211212122), we get a palindrome (342423324243).

It can be divided in two parts, 221212 and 112121, that added together give a palindrome (333333).

The spelling of 221212112121 in words is "two hundred twenty-one billion, two hundred twelve million, one hundred twelve thousand, one hundred twenty-one".