1991693371 has 4 divisors (see below), whose sum is σ = 2024344144. Its totient is φ = 1959042600.

The previous prime is 1991693369. The next prime is 1991693381. The reversal of 1991693371 is 1733961991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1733961991 = 89 ⋅19482719.

It is a cyclic number.

It is not a de Polignac number, because 1991693371 - 2¹ = 1991693369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991693321) 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 in 3 ways as a sum of consecutive naturals, for example, 16325295 + ... + 16325416.

It is an arithmetic number, because the mean of its divisors is an integer number (506086036).

Almost surely, 2^1991693371 is an apocalyptic number.

1991693371 is a deficient number, since it is larger than the sum of its proper divisors (32650773).

1991693371 is an equidigital number, since it uses as much as digits as its factorization.

1991693371 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32650772.

The product of its digits is 275562, while the sum is 49.

The square root of 1991693371 is about 44628.3919831311. The cubic root of 1991693371 is about 1258.1743466672.

The spelling of 1991693371 in words is "one billion, nine hundred ninety-one million, six hundred ninety-three thousand, three hundred seventy-one".