1991013113 has 4 divisors (see below), whose sum is σ = 1991109888. Its totient is φ = 1990916340.

The previous prime is 1991013077. The next prime is 1991013131. The reversal of 1991013113 is 3113101991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1991013113 - 2⁶ = 1991013049 is a prime.

It is a super-2 number, since 2×1991013113² = 7928266432275901538, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991013313) 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, 3881 + ... + 63222.

It is an arithmetic number, because the mean of its divisors is an integer number (497777472).

Almost surely, 2^1991013113 is an apocalyptic number.

It is an amenable number.

1991013113 is a deficient number, since it is larger than the sum of its proper divisors (96775).

1991013113 is an equidigital number, since it uses as much as digits as its factorization.

1991013113 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96774.

The product of its (nonzero) digits is 729, while the sum is 29.

The square root of 1991013113 is about 44620.7699731863. The cubic root of 1991013113 is about 1258.0310882324.

The spelling of 1991013113 in words is "one billion, nine hundred ninety-one million, thirteen thousand, one hundred thirteen".