165641 has 4 divisors (see below), whose sum is σ = 189312. Its totient is φ = 141972.

The previous prime is 165617. The next prime is 165653. The reversal of 165641 is 146561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 146561 = 113 ⋅1297.

It is a cyclic number.

It is not a de Polignac number, because 165641 - 2¹⁰ = 164617 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (165601) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 11825 + ... + 11838.

It is an arithmetic number, because the mean of its divisors is an integer number (47328).

2¹⁶⁵⁶⁴¹ is an apocalyptic number.

It is an amenable number.

165641 is a deficient number, since it is larger than the sum of its proper divisors (23671).

165641 is an equidigital number, since it uses as much as digits as its factorization.

165641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23670.

The product of its digits is 720, while the sum is 23.

The square root of 165641 is about 406.9901718715. The cubic root of 165641 is about 54.9189992227.

It can be divided in two parts, 1656 and 41, that multiplied together give a triangular number (67896 = T₃₆₈).

The spelling of 165641 in words is "one hundred sixty-five thousand, six hundred forty-one".