21111020010991 has 2 divisors, whose sum is σ = 21111020010992. Its totient is φ = 21111020010990.

The previous prime is 21111020010967. The next prime is 21111020011001. The reversal of 21111020010991 is 19901002011112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21111020010991 - 2¹¹ = 21111020008943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111020010491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555510005495 + 10555510005496.

It is an arithmetic number, because the mean of its divisors is an integer number (10555510005496).

Almost surely, 2^{21111020010991} is an apocalyptic number.

21111020010991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111020010991 is an equidigital number, since it uses as much as digits as its factorization.

21111020010991 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 28.

The spelling of 21111020010991 in words is "twenty-one trillion, one hundred eleven billion, twenty million, ten thousand, nine hundred ninety-one".