165640 has 32 divisors (see below), whose sum is σ = 385560. Its totient is φ = 64000.

The previous prime is 165617. The next prime is 165653. The reversal of 165640 is 46561.

It can be written as a sum of positive squares in 4 ways, for example, as 133956 + 31684 = 366^2 + 178^2 .

It is an Ulam number.

It is an unprimeable number.

165640 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1590 + ... + 1690.

2¹⁶⁵⁶⁴⁰ is an apocalyptic number.

165640 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 165640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (192780).

165640 is an abundant number, since it is smaller than the sum of its proper divisors (219920).

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

165640 is a wasteful number, since it uses less digits than its factorization.

165640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 165640 is about 406.9889433388. The cubic root of 165640 is about 54.9188887043.

The spelling of 165640 in words is "one hundred sixty-five thousand, six hundred forty".