165645 has 20 divisors (see below), whose sum is σ = 297660. Its totient is φ = 88128.

The previous prime is 165617. The next prime is 165653. The reversal of 165645 is 546561.

It is a happy number.

165645 is a `hidden beast` number, since 1 + 656 + 4 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 110889 + 54756 = 333^2 + 234^2 .

It is not a de Polignac number, because 165645 - 2⁹ = 165133 is a prime.

It is a super-3 number, since 3×165645³ = 13635034727133375, which contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 201 + ... + 609.

It is an arithmetic number, because the mean of its divisors is an integer number (14883).

2¹⁶⁵⁶⁴⁵ is an apocalyptic number.

165645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

165645 is a deficient number, since it is larger than the sum of its proper divisors (132015).

165645 is an equidigital number, since it uses as much as digits as its factorization.

165645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 426 (or 417 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

The square root of 165645 is about 406.9950859654. The cubic root of 165645 is about 54.9194412916.

The spelling of 165645 in words is "one hundred sixty-five thousand, six hundred forty-five".