161855 has 4 divisors (see below), whose sum is σ = 194232. Its totient is φ = 129480.

The previous prime is 161839. The next prime is 161869. The reversal of 161855 is 558161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 558161 = 17 ⋅32833.

It is not a de Polignac number, because 161855 - 2⁴ = 161839 is a prime.

It is a Duffinian number.

It is a congruent 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, 16181 + ... + 16190.

It is an arithmetic number, because the mean of its divisors is an integer number (48558).

2¹⁶¹⁸⁵⁵ is an apocalyptic number.

161855 is a deficient number, since it is larger than the sum of its proper divisors (32377).

161855 is an equidigital number, since it uses as much as digits as its factorization.

161855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32376.

The product of its digits is 1200, while the sum is 26.

The square root of 161855 is about 402.3120679274. The cubic root of 161855 is about 54.4973485790.

The spelling of 161855 in words is "one hundred sixty-one thousand, eight hundred fifty-five".