165990 has 32 divisors (see below), whose sum is σ = 435456. Its totient is φ = 40160.

The previous prime is 165983. The next prime is 166013. The reversal of 165990 is 99561.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable 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, 79 + ... + 581.

It is an arithmetic number, because the mean of its divisors is an integer number (13608).

2¹⁶⁵⁹⁹⁰ is an apocalyptic number.

165990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 165990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (217728).

165990 is an abundant number, since it is smaller than the sum of its proper divisors (269466).

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

165990 is a wasteful number, since it uses less digits than its factorization.

165990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 524.

The product of its (nonzero) digits is 2430, while the sum is 30.

The square root of 165990 is about 407.4187035471. The cubic root of 165990 is about 54.9575429915.

It can be divided in two parts, 16 and 5990, that added together give a palindrome (6006).

The spelling of 165990 in words is "one hundred sixty-five thousand, nine hundred ninety".