1897921811 has 2 divisors, whose sum is σ = 1897921812. Its totient is φ = 1897921810.

The previous prime is 1897921777. The next prime is 1897921813. The reversal of 1897921811 is 1181297981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1897921811 - 2¹⁸ = 1897659667 is a prime.

Together with 1897921813, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1897921813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 948960905 + 948960906.

It is an arithmetic number, because the mean of its divisors is an integer number (948960906).

Almost surely, 2^1897921811 is an apocalyptic number.

1897921811 is a deficient number, since it is larger than the sum of its proper divisors (1).

1897921811 is an equidigital number, since it uses as much as digits as its factorization.

1897921811 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 47.

The square root of 1897921811 is about 43565.1444505811. The cubic root of 1897921811 is about 1238.1105917996.

The spelling of 1897921811 in words is "one billion, eight hundred ninety-seven million, nine hundred twenty-one thousand, eight hundred eleven".