161666 has 4 divisors (see below), whose sum is σ = 242502. Its totient is φ = 80832.

The previous prime is 161659. The next prime is 161683. The reversal of 161666 is 666161.

161666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 666161 = 229 ⋅2909.

It can be written as a sum of positive squares in only one way, i.e., 137641 + 24025 = 371^2 + 155^2 .

It is a super-2 number, since 2×161666² = 52271791112, which contains 22 as substring.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 161666.

It is an unprimeable number.

161666 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40415 + ... + 40418.

2¹⁶¹⁶⁶⁶ is an apocalyptic number.

161666 is a deficient number, since it is larger than the sum of its proper divisors (80836).

161666 is an equidigital number, since it uses as much as digits as its factorization.

161666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80835.

The product of its digits is 1296, while the sum is 26.

The square root of 161666 is about 402.0771070330. The cubic root of 161666 is about 54.4761279173.

The spelling of 161666 in words is "one hundred sixty-one thousand, six hundred sixty-six".