1221221221221 has 4 divisors (see below), whose sum is σ = 1628294961632. Its totient is φ = 814147480812.

The previous prime is 1221221221189. The next prime is 1221221221249.

1221221221221 is nontrivially palindromic in base 10.

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 not a de Polignac number, because 1221221221221 - 2⁵ = 1221221221189 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221221221291) 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 3 ways as a sum of consecutive naturals, for example, 203536870201 + ... + 203536870206.

It is an arithmetic number, because the mean of its divisors is an integer number (407073740408).

Almost surely, 2^{1221221221221} is an apocalyptic number.

It is an amenable number.

1221221221221 is a deficient number, since it is larger than the sum of its proper divisors (407073740411).

1221221221221 is an equidigital number, since it uses as much as digits as its factorization.

1221221221221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407073740410.

The product of its digits is 256, while the sum is 21.

The spelling of 1221221221221 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, two hundred twenty-one thousand, two hundred twenty-one".