2163891991 has 2 divisors, whose sum is σ = 2163891992. Its totient is φ = 2163891990.

The previous prime is 2163891901. The next prime is 2163892001. The reversal of 2163891991 is 1991983612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2163891991 - 2⁹ = 2163891479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2163891901) 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, 1081945995 + 1081945996.

It is an arithmetic number, because the mean of its divisors is an integer number (1081945996).

Almost surely, 2^2163891991 is an apocalyptic number.

2163891991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2163891991 is an equidigital number, since it uses as much as digits as its factorization.

2163891991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 209952, while the sum is 49.

The square root of 2163891991 is about 46517.6524665637. The cubic root of 2163891991 is about 1293.4367408034.

The spelling of 2163891991 in words is "two billion, one hundred sixty-three million, eight hundred ninety-one thousand, nine hundred ninety-one".