165688393 has 8 divisors (see below), whose sum is σ = 180072200. Its totient is φ = 151538688.

The previous prime is 165688373. The next prime is 165688403. The reversal of 165688393 is 393886561.

It can be written as a sum of positive squares in 4 ways, for example, as 24482704 + 141205689 = 4948^2 + 11883^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165688393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165688373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57048 + ... + 59881.

It is an arithmetic number, because the mean of its divisors is an integer number (22509025).

Almost surely, 2^165688393 is an apocalyptic number.

165688393 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

165688393 is a deficient number, since it is larger than the sum of its proper divisors (14383807).

165688393 is a wasteful number, since it uses less digits than its factorization.

165688393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117051.

The product of its digits is 933120, while the sum is 49.

The square root of 165688393 is about 12872.0003495960. Note that the first 3 decimals coincide. The cubic root of 165688393 is about 549.2423650879.

The spelling of 165688393 in words is "one hundred sixty-five million, six hundred eighty-eight thousand, three hundred ninety-three".