20102011991 has 2 divisors, whose sum is σ = 20102011992. Its totient is φ = 20102011990.

The previous prime is 20102011939. The next prime is 20102011999. The reversal of 20102011991 is 19911020102.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20102011991 - 2⁶ = 20102011927 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20102011991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20102011999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10051005995 + 10051005996.

It is an arithmetic number, because the mean of its divisors is an integer number (10051005996).

Almost surely, 2^20102011991 is an apocalyptic number.

20102011991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20102011991 is an equidigital number, since it uses as much as digits as its factorization.

20102011991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 26.

The spelling of 20102011991 in words is "twenty billion, one hundred two million, eleven thousand, nine hundred ninety-one".