1221211021221 has 8 divisors (see below), whose sum is σ = 1809201512960. Its totient is φ = 814140680796.

The previous prime is 1221211021213. The next prime is 1221211021223. The reversal of 1221211021221 is 1221201121221.

1221211021221 is a `hidden beast` number, since 1 + 221 + 211 + 0 + 212 + 21 = 666.

It is not a de Polignac number, because 1221211021221 - 2³ = 1221211021213 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1221211021194 and 1221211021203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221211021223) 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 7 ways as a sum of consecutive naturals, for example, 22615018885 + ... + 22615018938.

It is an arithmetic number, because the mean of its divisors is an integer number (226150189120).

Almost surely, 2^{1221211021221} is an apocalyptic number.

It is an amenable number.

1221211021221 is a deficient number, since it is larger than the sum of its proper divisors (587990491739).

1221211021221 is an equidigital number, since it uses as much as digits as its factorization.

1221211021221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45230037832 (or 45230037826 counting only the distinct ones).

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

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

The spelling of 1221211021221 in words is "one trillion, two hundred twenty-one billion, two hundred eleven million, twenty-one thousand, two hundred twenty-one".