1221220112221 has 4 divisors (see below), whose sum is σ = 1247203518912. Its totient is φ = 1195236705532.

The previous prime is 1221220112219. The next prime is 1221220112227. The reversal of 1221220112221 is 1222110221221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1221220112221 - 2¹ = 1221220112219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221220112227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12991703275 + ... + 12991703368.

It is an arithmetic number, because the mean of its divisors is an integer number (311800879728).

Almost surely, 2^{1221220112221} is an apocalyptic number.

It is an amenable number.

1221220112221 is a deficient number, since it is larger than the sum of its proper divisors (25983406691).

1221220112221 is an equidigital number, since it uses as much as digits as its factorization.

1221220112221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25983406690.

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

Adding to 1221220112221 its reverse (1222110221221), we get a palindrome (2443330333442).

The spelling of 1221220112221 in words is "one trillion, two hundred twenty-one billion, two hundred twenty million, one hundred twelve thousand, two hundred twenty-one".