171 has 6 divisors (see below), whose sum is σ = 260. Its totient is φ = 108.

The previous prime is 167. The next prime is 173.

171 is nontrivially palindromic in base 7 and base 10.

171 is an esthetic number in base 9, base 12 and base 16, because in such bases it adjacent digits differ by 1.

171 is a nontrivial binomial coefficient, being equal to C(19, 2).

It is not a de Polignac number, because 171 - 2^{2} = 167 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 19 = 171 / (1 + 7 + 1).

It is the 9-th Jacobsthal number.

It is a Duffinian number.

171 is an undulating number in base 10.

171 is a lucky number.

171 is a nontrivial repdigit in base 7.

It is a plaindrome in base 4, base 7, base 11, base 12 and base 16.

It is a nialpdrome in base 6, base 7, base 9, base 14 and base 15.

It is a zygodrome in base 7.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1 + ... + 18.

171 is the 18-th triangular number.

171 is a deficient number, since it is larger than the sum of its proper divisors (89).

171 is a wasteful number, since it uses less digits than its factorization.

With its predecessor (170) it forms an eRAP, since the sums of their prime factors are consecutive (24 and 25).

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

The sum of its prime factors is 25 (or 22 counting only the distinct ones).

The product of its digits is 7, while the sum is 9.

The square root of 171 is about 13.0766968306. The cubic root of 171 is about 5.5504991029.

The spelling of 171 in words is "one hundred seventy-one", and is thus an aban number and an iban number.

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