1991793919 has 2 divisors, whose sum is σ = 1991793920. Its totient is φ = 1991793918.

The previous prime is 1991793917. The next prime is 1991793931. The reversal of 1991793919 is 9193971991.

It is a weak prime.

It is an emirp because it is prime and its reverse (9193971991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1991793919 - 2¹ = 1991793917 is a prime.

It is a super-2 number, since 2×1991793919² = 7934486031530757122, which contains 22 as substring.

Together with 1991793917, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1991793917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995896959 + 995896960.

It is an arithmetic number, because the mean of its divisors is an integer number (995896960).

Almost surely, 2^1991793919 is an apocalyptic number.

1991793919 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991793919 is an equidigital number, since it uses as much as digits as its factorization.

1991793919 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1240029, while the sum is 58.

The square root of 1991793919 is about 44629.5184715229. The cubic root of 1991793919 is about 1258.1955187324.

The spelling of 1991793919 in words is "one billion, nine hundred ninety-one million, seven hundred ninety-three thousand, nine hundred nineteen".