1221320312021 has 4 divisors (see below), whose sum is σ = 1221337774272. Its totient is φ = 1221302849772.

The previous prime is 1221320311957. The next prime is 1221320312029. The reversal of 1221320312021 is 1202130231221.

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 1221320312021 - 2⁶ = 1221320311957 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 = 1221320311984 and 1221320312002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221320312029) 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, 8625791 + ... + 8766236.

It is an arithmetic number, because the mean of its divisors is an integer number (305334443568).

Almost surely, 2^{1221320312021} is an apocalyptic number.

It is an amenable number.

1221320312021 is a deficient number, since it is larger than the sum of its proper divisors (17462251).

1221320312021 is an equidigital number, since it uses as much as digits as its factorization.

1221320312021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17462250.

The product of its (nonzero) digits is 288, while the sum is 20.

Adding to 1221320312021 its reverse (1202130231221), we get a palindrome (2423450543242).

The spelling of 1221320312021 in words is "one trillion, two hundred twenty-one billion, three hundred twenty million, three hundred twelve thousand, twenty-one".