1221211111221 has 12 divisors (see below), whose sum is σ = 1781436671820. Its totient is φ = 806079940800.

The previous prime is 1221211111111. The next prime is 1221211111259. The reversal of 1221211111221 is 1221111121221.

It is a happy number.

1221211111221 is a `hidden beast` number, since 1 + 221 + 211 + 1 + 11 + 221 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 837021882321 + 384189228900 = 914889^2 + 619830^2 .

It is not a de Polignac number, because 1221211111221 - 2¹⁹ = 1221210586933 is a prime.

It is a super-2 number, since 2×1221211111221² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1221211111194 and 1221211111203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221211151221) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 671732376 + ... + 671734193.

It is an arithmetic number, because the mean of its divisors is an integer number (148453055985).

Almost surely, 2^{1221211111221} is an apocalyptic number.

It is an amenable number.

1221211111221 is a deficient number, since it is larger than the sum of its proper divisors (560225560599).

1221211111221 is a wasteful number, since it uses less digits than its factorization.

1221211111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1343466676 (or 1343466673 counting only the distinct ones).

The product of its digits is 32, while the sum is 18.

Adding to 1221211111221 its reverse (1221111121221), we get a palindrome (2442322232442).

The spelling of 1221211111221 in words is "one trillion, two hundred twenty-one billion, two hundred eleven million, one hundred eleven thousand, two hundred twenty-one".