165989999 has 6 divisors (see below), whose sum is σ = 193090464. Its totient is φ = 142277100.

The previous prime is 165989987. The next prime is 165990037. The reversal of 165989999 is 999989561.

It is not a de Polignac number, because 165989999 - 2²⁴ = 149212783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165989099) 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 5 ways as a sum of consecutive naturals, for example, 1693727 + ... + 1693824.

It is an arithmetic number, because the mean of its divisors is an integer number (32181744).

Almost surely, 2^165989999 is an apocalyptic number.

165989999 is a deficient number, since it is larger than the sum of its proper divisors (27100465).

165989999 is an equidigital number, since it uses as much as digits as its factorization.

165989999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3387565 (or 3387558 counting only the distinct ones).

The product of its digits is 14171760, while the sum is 65.

The square root of 165989999 is about 12883.7106068089. The cubic root of 165989999 is about 549.5754288114.

The spelling of 165989999 in words is "one hundred sixty-five million, nine hundred eighty-nine thousand, nine hundred ninety-nine".