165891985 has 16 divisors (see below), whose sum is σ = 237401856. Its totient is φ = 108808128.

The previous prime is 165891959. The next prime is 165892033. The reversal of 165891985 is 589198561.

It is a cyclic number.

It is not a de Polignac number, because 165891985 - 2⁵ = 165891953 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 102234 + ... + 103843.

It is an arithmetic number, because the mean of its divisors is an integer number (14837616).

Almost surely, 2^165891985 is an apocalyptic number.

It is an amenable number.

165891985 is a deficient number, since it is larger than the sum of its proper divisors (71509871).

165891985 is a wasteful number, since it uses less digits than its factorization.

165891985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206112.

The product of its digits is 777600, while the sum is 52.

The square root of 165891985 is about 12879.9062496588. The cubic root of 165891985 is about 549.4672361649.

The spelling of 165891985 in words is "one hundred sixty-five million, eight hundred ninety-one thousand, nine hundred eighty-five".