2021011219921 has 2 divisors, whose sum is σ = 2021011219922. Its totient is φ = 2021011219920.

The previous prime is 2021011219919. The next prime is 2021011220017. The reversal of 2021011219921 is 1299121101202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1964314371600 + 56696848321 = 1401540^2 + 238111^2 .

It is a cyclic number.

It is not a de Polignac number, because 2021011219921 - 2¹ = 2021011219919 is a prime.

Together with 2021011219919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (2021011214921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1010505609960 + 1010505609961.

It is an arithmetic number, because the mean of its divisors is an integer number (1010505609961).

Almost surely, 2^{2021011219921} is an apocalyptic number.

It is an amenable number.

2021011219921 is a deficient number, since it is larger than the sum of its proper divisors (1).

2021011219921 is an equidigital number, since it uses as much as digits as its factorization.

2021011219921 is an evil number, because the sum of its binary digits is even.

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

The spelling of 2021011219921 in words is "two trillion, twenty-one billion, eleven million, two hundred nineteen thousand, nine hundred twenty-one".