21110101209991 has 2 divisors, whose sum is σ = 21110101209992. Its totient is φ = 21110101209990.

The previous prime is 21110101209983. The next prime is 21110101210001. The reversal of 21110101209991 is 19990210101112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21110101209991 - 2³ = 21110101209983 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21110101209991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21110101209091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555050604995 + 10555050604996.

It is an arithmetic number, because the mean of its divisors is an integer number (10555050604996).

Almost surely, 2^{21110101209991} is an apocalyptic number.

21110101209991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21110101209991 is an equidigital number, since it uses as much as digits as its factorization.

21110101209991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2916, while the sum is 37.

The spelling of 21110101209991 in words is "twenty-one trillion, one hundred ten billion, one hundred one million, two hundred nine thousand, nine hundred ninety-one".