1021100101991 has 2 divisors, whose sum is σ = 1021100101992. Its totient is φ = 1021100101990.

The previous prime is 1021100101939. The next prime is 1021100101997. The reversal of 1021100101991 is 1991010011201.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1021100101991 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1021100101991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1021100101997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510550050995 + 510550050996.

It is an arithmetic number, because the mean of its divisors is an integer number (510550050996).

Almost surely, 2^{1021100101991} is an apocalyptic number.

1021100101991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021100101991 is an equidigital number, since it uses as much as digits as its factorization.

1021100101991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162, while the sum is 26.

The spelling of 1021100101991 in words is "one trillion, twenty-one billion, one hundred million, one hundred one thousand, nine hundred ninety-one".