1091992991 has 4 divisors (see below), whose sum is σ = 1092063000. Its totient is φ = 1091922984.

The previous prime is 1091992987. The next prime is 1091992997. The reversal of 1091992991 is 1992991901.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1992991901 = 47 ⋅42404083.

It is a cyclic number.

It is not a de Polignac number, because 1091992991 - 2² = 1091992987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1091992997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 185 + ... + 46733.

It is an arithmetic number, because the mean of its divisors is an integer number (273015750).

Almost surely, 2^1091992991 is an apocalyptic number.

1091992991 is a deficient number, since it is larger than the sum of its proper divisors (70009).

1091992991 is an equidigital number, since it uses as much as digits as its factorization.

1091992991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70008.

The product of its (nonzero) digits is 118098, while the sum is 50.

The square root of 1091992991 is about 33045.3172325520. The cubic root of 1091992991 is about 1029.7693237153.

The spelling of 1091992991 in words is "one billion, ninety-one million, nine hundred ninety-two thousand, nine hundred ninety-one".