165540 has 48 divisors (see below), whose sum is σ = 483840. Its totient is φ = 42240.

The previous prime is 165533. The next prime is 165541. The reversal of 165540 is 45561.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165541) by changing a digit.

165540 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1816 + ... + 1904.

It is an arithmetic number, because the mean of its divisors is an integer number (10080).

2¹⁶⁵⁵⁴⁰ is an apocalyptic number.

165540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 165540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (241920).

165540 is an abundant number, since it is smaller than the sum of its proper divisors (318300).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

165540 is a wasteful number, since it uses less digits than its factorization.

165540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 165540 is about 406.8660713306. The cubic root of 165540 is about 54.9078346223.

Adding to 165540 its sum of digits (21), we get a palindrome (165561).

The spelling of 165540 in words is "one hundred sixty-five thousand, five hundred forty".