1221201121221 has 12 divisors (see below), whose sum is σ = 1766892219820. Its totient is φ = 812779444800.

The previous prime is 1221201121219. The next prime is 1221201121247. The reversal of 1221201121221 is 1221211021221.

1221201121221 is a `hidden beast` number, since 1 + 221 + 201 + 1 + 21 + 221 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1145788272225 + 75412848996 = 1070415^2 + 274614^2 .

It is not a de Polignac number, because 1221201121221 - 2¹ = 1221201121219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221201121194 and 1221201121203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221201121271) 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 11 ways as a sum of consecutive naturals, for example, 112880626 + ... + 112891443.

Almost surely, 2^{1221201121221} is an apocalyptic number.

It is an amenable number.

1221201121221 is a deficient number, since it is larger than the sum of its proper divisors (545691098599).

1221201121221 is a wasteful number, since it uses less digits than its factorization.

1221201121221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225772676 (or 225772673 counting only the distinct ones).

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

Adding to 1221201121221 its reverse (1221211021221), we get a palindrome (2442412142442).

The spelling of 1221201121221 in words is "one trillion, two hundred twenty-one billion, two hundred one million, one hundred twenty-one thousand, two hundred twenty-one".