161765 has 4 divisors (see below), whose sum is σ = 194124. Its totient is φ = 129408.

The previous prime is 161761. The next prime is 161771. The reversal of 161765 is 567161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 567161 = 7 ⋅81023.

It can be written as a sum of positive squares in 2 ways, for example, as 103684 + 58081 = 322^2 + 241^2 .

It is a cyclic number.

It is not a de Polignac number, because 161765 - 2² = 161761 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 161765.

It is not an unprimeable number, because it can be changed into a prime (161761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16172 + ... + 16181.

It is an arithmetic number, because the mean of its divisors is an integer number (48531).

2¹⁶¹⁷⁶⁵ is an apocalyptic number.

It is an amenable number.

161765 is a deficient number, since it is larger than the sum of its proper divisors (32359).

161765 is an equidigital number, since it uses as much as digits as its factorization.

161765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32358.

The product of its digits is 1260, while the sum is 26.

The square root of 161765 is about 402.2001989060. The cubic root of 161765 is about 54.4872455635.

The spelling of 161765 in words is "one hundred sixty-one thousand, seven hundred sixty-five".