2097171991 has 2 divisors, whose sum is σ = 2097171992. Its totient is φ = 2097171990.

The previous prime is 2097171863. The next prime is 2097171997. The reversal of 2097171991 is 1991717902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2097171991 - 2⁷ = 2097171863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2097171997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1048585995 + 1048585996.

It is an arithmetic number, because the mean of its divisors is an integer number (1048585996).

Almost surely, 2^2097171991 is an apocalyptic number.

2097171991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2097171991 is an equidigital number, since it uses as much as digits as its factorization.

2097171991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 71442, while the sum is 46.

The square root of 2097171991 is about 45794.8904464243. The cubic root of 2097171991 is about 1280.0040671664.

The spelling of 2097171991 in words is "two billion, ninety-seven million, one hundred seventy-one thousand, nine hundred ninety-one".