1897197091 has 2 divisors, whose sum is σ = 1897197092. Its totient is φ = 1897197090.

The previous prime is 1897197053. The next prime is 1897197149. The reversal of 1897197091 is 1907917981.

It is a weak prime.

It is an emirp because it is prime and its reverse (1907917981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1897197091 - 2¹⁹ = 1896672803 is a prime.

It is not a weakly prime, because it can be changed into another prime (1897197031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 948598545 + 948598546.

It is an arithmetic number, because the mean of its divisors is an integer number (948598546).

Almost surely, 2^1897197091 is an apocalyptic number.

1897197091 is a deficient number, since it is larger than the sum of its proper divisors (1).

1897197091 is an equidigital number, since it uses as much as digits as its factorization.

1897197091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 285768, while the sum is 52.

The square root of 1897197091 is about 43556.8259977699. The cubic root of 1897197091 is about 1237.9529812075.

The spelling of 1897197091 in words is "one billion, eight hundred ninety-seven million, one hundred ninety-seven thousand, ninety-one".