172116181 has 4 divisors (see below), whose sum is σ = 172144012. Its totient is φ = 172088352.

The previous prime is 172116179. The next prime is 172116223. The reversal of 172116181 is 181611271.

172116181 is a nontrivial binomial coefficient, being equal to C(18554, 2).

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 181611271 = 10903 ⋅16657.

It can be written as a sum of positive squares in 2 ways, for example, as 70711281 + 101404900 = 8409^2 + 10070^2 .

It is a 3-Lehmer number, since φ(172116181) divides (172116181-1)³.

It is a cyclic number.

It is not a de Polignac number, because 172116181 - 2¹ = 172116179 is a prime.

It is a super-2 number, since 2×172116181² = 59247959524049522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (170116181) by changing a digit.

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, 1 + ... + 18553.

It is an arithmetic number, because the mean of its divisors is an integer number (43036003).

It is a Poulet number, since it divides 2^172116180-1.

Almost surely, 2^172116181 is an apocalyptic number.

172116181 is the 18553-rd triangular number and also the 9277-th hexagonal number.

172116181 is the 6185-th centered nonagonal number.

It is an amenable number.

172116181 is a deficient number, since it is larger than the sum of its proper divisors (27831).

172116181 is an equidigital number, since it uses as much as digits as its factorization.

172116181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27830.

The product of its digits is 672, while the sum is 28.

The square root of 172116181 is about 13119.3056599806. The cubic root of 172116181 is about 556.2549649685.

The spelling of 172116181 in words is "one hundred seventy-two million, one hundred sixteen thousand, one hundred eighty-one".