221221212121 has 32 divisors (see below), whose sum is σ = 273851020800. Its totient is φ = 174018392064.

The previous prime is 221221212089. The next prime is 221221212127. The reversal of 221221212121 is 121212122122.

It is a cyclic number.

It is not a de Polignac number, because 221221212121 - 2⁵ = 221221212089 is a prime.

221221212121 is a modest number, since divided by 21212121 gives 2212 as remainder.

It is not an unprimeable number, because it can be changed into a prime (221221212127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40971780 + ... + 40977178.

It is an arithmetic number, because the mean of its divisors is an integer number (8557844400).

Almost surely, 2^221221212121 is an apocalyptic number.

It is an amenable number.

221221212121 is a deficient number, since it is larger than the sum of its proper divisors (52629808679).

221221212121 is a wasteful number, since it uses less digits than its factorization.

221221212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7945.

The product of its digits is 128, while the sum is 19.

Adding to 221221212121 its reverse (121212122122), we get a palindrome (342433334243).

The spelling of 221221212121 in words is "two hundred twenty-one billion, two hundred twenty-one million, two hundred twelve thousand, one hundred twenty-one".