1991065379 has 2 divisors, whose sum is σ = 1991065380. Its totient is φ = 1991065378.

The previous prime is 1991065343. The next prime is 1991065399. The reversal of 1991065379 is 9735601991.

It is a strong prime.

It is an emirp because it is prime and its reverse (9735601991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1991065379 - 2⁸ = 1991065123 is a prime.

It is not a weakly prime, because it can be changed into another prime (1991065399) 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, 995532689 + 995532690.

It is an arithmetic number, because the mean of its divisors is an integer number (995532690).

Almost surely, 2^1991065379 is an apocalyptic number.

1991065379 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991065379 is an equidigital number, since it uses as much as digits as its factorization.

1991065379 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 459270, while the sum is 50.

The square root of 1991065379 is about 44621.3556383040. The cubic root of 1991065379 is about 1258.0420963095.

The spelling of 1991065379 in words is "one billion, nine hundred ninety-one million, sixty-five thousand, three hundred seventy-nine".