1021201219921 has 2 divisors, whose sum is σ = 1021201219922. Its totient is φ = 1021201219920.

The previous prime is 1021201219919. The next prime is 1021201219931. The reversal of 1021201219921 is 1299121021201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 710461866321 + 310739353600 = 842889^2 + 557440^2 .

It is an emirp because it is prime and its reverse (1299121021201) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1021201219921 - 2¹ = 1021201219919 is a prime.

Together with 1021201219919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1021201219931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510600609960 + 510600609961.

It is an arithmetic number, because the mean of its divisors is an integer number (510600609961).

Almost surely, 2^{1021201219921} is an apocalyptic number.

It is an amenable number.

1021201219921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021201219921 is an equidigital number, since it uses as much as digits as its factorization.

1021201219921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 31.

The spelling of 1021201219921 in words is "one trillion, twenty-one billion, two hundred one million, two hundred nineteen thousand, nine hundred twenty-one".