1221220211221 has 32 divisors (see below), whose sum is σ = 1367882968320. Its totient is φ = 1083480883200.

The previous prime is 1221220211209. The next prime is 1221220211249. The reversal of 1221220211221 is 1221120221221.

It is not a de Polignac number, because 1221220211221 - 2⁹ = 1221220210709 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221220251221) 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 31 ways as a sum of consecutive naturals, for example, 105938560 + ... + 105950086.

It is an arithmetic number, because the mean of its divisors is an integer number (42746342760).

Almost surely, 2^{1221220211221} is an apocalyptic number.

It is an amenable number.

1221220211221 is a deficient number, since it is larger than the sum of its proper divisors (146662757099).

1221220211221 is a wasteful number, since it uses less digits than its factorization.

1221220211221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13165.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 1221220211221 its reverse (1221120221221), we get a palindrome (2442340432442).

The spelling of 1221220211221 in words is "one trillion, two hundred twenty-one billion, two hundred twenty million, two hundred eleven thousand, two hundred twenty-one".