2021111101991 has 2 divisors, whose sum is σ = 2021111101992. Its totient is φ = 2021111101990.

The previous prime is 2021111101957. The next prime is 2021111102081. The reversal of 2021111101991 is 1991011111202.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2021111101991 - 2⁶ = 2021111101927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2021111100991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1010555550995 + 1010555550996.

It is an arithmetic number, because the mean of its divisors is an integer number (1010555550996).

Almost surely, 2^{2021111101991} is an apocalyptic number.

2021111101991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2021111101991 is an equidigital number, since it uses as much as digits as its factorization.

2021111101991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 29.

The spelling of 2021111101991 in words is "two trillion, twenty-one billion, one hundred eleven million, one hundred one thousand, nine hundred ninety-one".