21110211120991 has 2 divisors, whose sum is σ = 21110211120992. Its totient is φ = 21110211120990.

The previous prime is 21110211120979. The next prime is 21110211121019. The reversal of 21110211120991 is 19902111201112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21110211120991 - 2⁷ = 21110211120863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21110211120941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555105560495 + 10555105560496.

It is an arithmetic number, because the mean of its divisors is an integer number (10555105560496).

Almost surely, 2^{21110211120991} is an apocalyptic number.

21110211120991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21110211120991 is an equidigital number, since it uses as much as digits as its factorization.

21110211120991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 31.

The spelling of 21110211120991 in words is "twenty-one trillion, one hundred ten billion, two hundred eleven million, one hundred twenty thousand, nine hundred ninety-one".