1991034889 has 4 divisors (see below), whose sum is σ = 1995633556. Its totient is φ = 1986436224.

The previous prime is 1991034887. The next prime is 1991034911. The reversal of 1991034889 is 9884301991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 365574400 + 1625460489 = 19120^2 + 40317^2 .

It is a cyclic number.

It is not a de Polignac number, because 1991034889 - 2¹ = 1991034887 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991034887) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2298684 + ... + 2299549.

It is an arithmetic number, because the mean of its divisors is an integer number (498908389).

Almost surely, 2^1991034889 is an apocalyptic number.

It is an amenable number.

1991034889 is a deficient number, since it is larger than the sum of its proper divisors (4598667).

1991034889 is an equidigital number, since it uses as much as digits as its factorization.

1991034889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4598666.

The product of its (nonzero) digits is 559872, while the sum is 52.

The square root of 1991034889 is about 44621.0139844446. The cubic root of 1991034889 is about 1258.0356746387.

The spelling of 1991034889 in words is "one billion, nine hundred ninety-one million, thirty-four thousand, eight hundred eighty-nine".