20101011991 has 2 divisors, whose sum is σ = 20101011992. Its totient is φ = 20101011990.

The previous prime is 20101011979. The next prime is 20101012003. The reversal of 20101011991 is 19911010102.

It is a balanced prime because it is at equal distance from previous prime (20101011979) and next prime (20101012003).

It is a cyclic number.

It is not a de Polignac number, because 20101011991 - 2⁷ = 20101011863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20101014991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10050505995 + 10050505996.

It is an arithmetic number, because the mean of its divisors is an integer number (10050505996).

Almost surely, 2^20101011991 is an apocalyptic number.

20101011991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20101011991 is an equidigital number, since it uses as much as digits as its factorization.

20101011991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 162, while the sum is 25.

The spelling of 20101011991 in words is "twenty billion, one hundred one million, eleven thousand, nine hundred ninety-one".