1221112211221 has 16 divisors (see below), whose sum is σ = 1441131429888. Its totient is φ = 1012512740400.

The previous prime is 1221112211177. The next prime is 1221112211237. The reversal of 1221112211221 is 1221122111221.

It is a happy number.

It is not a de Polignac number, because 1221112211221 - 2⁹ = 1221112210709 is a prime.

It is a super-2 number, since 2×1221112211221² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221112211621) 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 15 ways as a sum of consecutive naturals, for example, 523675 + ... + 1648168.

It is an arithmetic number, because the mean of its divisors is an integer number (90070714368).

Almost surely, 2^{1221112211221} is an apocalyptic number.

It is an amenable number.

1221112211221 is a deficient number, since it is larger than the sum of its proper divisors (220019218667).

1221112211221 is a wasteful number, since it uses less digits than its factorization.

1221112211221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2174472.

The product of its digits is 64, while the sum is 19.

Adding to 1221112211221 its reverse (1221122111221), we get a palindrome (2442234322442).

It can be divided in two parts, 122111 and 2211221, that added together give a palindrome (2333332).

The spelling of 1221112211221 in words is "one trillion, two hundred twenty-one billion, one hundred twelve million, two hundred eleven thousand, two hundred twenty-one".