7921111012021 has 2 divisors, whose sum is σ = 7921111012022. Its totient is φ = 7921111012020.

The previous prime is 7921111012019. The next prime is 7921111012037. The reversal of 7921111012021 is 1202101111297.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6902547652900 + 1018563359121 = 2627270^2 + 1009239^2 .

It is an emirp because it is prime and its reverse (1202101111297) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7921111012021 - 2¹ = 7921111012019 is a prime.

Together with 7921111012019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7921111012621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3960555506010 + 3960555506011.

It is an arithmetic number, because the mean of its divisors is an integer number (3960555506011).

Almost surely, 2^{7921111012021} is an apocalyptic number.

It is an amenable number.

7921111012021 is a deficient number, since it is larger than the sum of its proper divisors (1).

7921111012021 is an equidigital number, since it uses as much as digits as its factorization.

7921111012021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 28.

The spelling of 7921111012021 in words is "seven trillion, nine hundred twenty-one billion, one hundred eleven million, twelve thousand, twenty-one".