1221001211221 has 12 divisors (see below), whose sum is σ = 1343198825836. Its totient is φ = 1109085880320.

The previous prime is 1221001211191. The next prime is 1221001211231. The reversal of 1221001211221 is 1221121001221.

It can be written as a sum of positive squares in 2 ways, for example, as 717595352100 + 503405859121 = 847110^2 + 709511^2 .

It is not a de Polignac number, because 1221001211221 - 2¹⁷ = 1221001080149 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221001211195 and 1221001211204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221001211231) 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, 4012716 + ... + 4306261.

Almost surely, 2^{1221001211221} is an apocalyptic number.

1221001211221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221001211221 is a deficient number, since it is larger than the sum of its proper divisors (122197614615).

1221001211221 is a wasteful number, since it uses less digits than its factorization.

1221001211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8320212 (or 8320201 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 1221001211221 its reverse (1221121001221), we get a palindrome (2442122212442).

The spelling of 1221001211221 in words is "one trillion, two hundred twenty-one billion, one million, two hundred eleven thousand, two hundred twenty-one".