985999991 has 4 divisors (see below), whose sum is σ = 987534072. Its totient is φ = 984465912.

The previous prime is 985999979. The next prime is 986000009. The reversal of 985999991 is 199999589.

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

It is a cyclic number.

It is not a de Polignac number, because 985999991 - 2¹⁰ = 985998967 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 (985999921) 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, 766076 + ... + 767361.

It is an arithmetic number, because the mean of its divisors is an integer number (246883518).

Almost surely, 2^985999991 is an apocalyptic number.

985999991 is a deficient number, since it is larger than the sum of its proper divisors (1534081).

985999991 is a wasteful number, since it uses less digits than its factorization.

985999991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1534080.

The product of its digits is 21257640, while the sum is 68.

The square root of 985999991 is about 31400.6367929060. The cubic root of 985999991 is about 995.3113815472.

The spelling of 985999991 in words is "nine hundred eighty-five million, nine hundred ninety-nine thousand, nine hundred ninety-one".