161705 has 4 divisors (see below), whose sum is σ = 194052. Its totient is φ = 129360.

The previous prime is 161683. The next prime is 161717. The reversal of 161705 is 507161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 507161 = 17 ⋅29833.

It can be written as a sum of positive squares in 2 ways, for example, as 34969 + 126736 = 187^2 + 356^2 .

It is not a de Polignac number, because 161705 - 2⁶ = 161641 is a prime.

It is a super-2 number, since 2×161705² = 52297014050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16166 + ... + 16175.

It is an arithmetic number, because the mean of its divisors is an integer number (48513).

2¹⁶¹⁷⁰⁵ is an apocalyptic number.

It is an amenable number.

161705 is a deficient number, since it is larger than the sum of its proper divisors (32347).

161705 is an equidigital number, since it uses as much as digits as its factorization.

161705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32346.

The product of its (nonzero) digits is 210, while the sum is 20.

The square root of 161705 is about 402.1256022687. The cubic root of 161705 is about 54.4805081377.

Adding to 161705 its reverse (507161), we get a palindrome (668866).

The spelling of 161705 in words is "one hundred sixty-one thousand, seven hundred five".