166 has 4 divisors (see below), whose sum is σ = 252. Its totient is φ = 82.

The previous prime is 163. The next prime is 167. The reversal of 166 is 661.

Subtracting from 166 its sum of digits (13), we obtain a triangular number (153 = T_{17}).

Adding to 166 its product of digits (36), we get a palindrome (202).

It can be divided in two parts, 16 and 6, that added together give a palindrome (22).

166 = T_{9} + T_{10} +
T_{11}.

166 is nontrivially palindromic in base 6 and base 11.

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

166 is an esthetic number in base 6 and base 14, because in such bases its adjacent digits differ by 1.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

166 is an undulating number in base 6 and base 11.

It is a plaindrome in base 8, base 10, base 12 and base 14.

It is a nialpdrome in base 13, base 15 and base 16.

It is a congruent number.

It is a panconsummate number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40 + ... + 43.

It is an arithmetic number, because the mean of its divisors is an integer number (63).

166 is the 11-th centered triangular number.

166 is a deficient number, since it is larger than the sum of its proper divisors (86).

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

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

The sum of its prime factors is 85.

The product of its digits is 36, while the sum is 13.

The square root of 166 is about 12.8840987267. The cubic root of 166 is about 5.4958646601.

The spelling of 166 in words is "one hundred sixty-six", and thus it is an aban number.

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