81182173 has 4 divisors (see below), whose sum is σ = 83162268. Its totient is φ = 79202080.

The previous prime is 81182161. The next prime is 81182177. The reversal of 81182173 is 37128118.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2647129 + 78535044 = 1627^2 + 8862^2 .

It is a cyclic number.

It is not a de Polignac number, because 81182173 - 2¹⁷ = 81051101 is a prime.

It is a super-3 number, since 3×81182173³ (a number of 25 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81182177) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 989986 + ... + 990067.

It is an arithmetic number, because the mean of its divisors is an integer number (20790567).

Almost surely, 2^81182173 is an apocalyptic number.

It is an amenable number.

81182173 is a deficient number, since it is larger than the sum of its proper divisors (1980095).

81182173 is a wasteful number, since it uses less digits than its factorization.

81182173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1980094.

The product of its digits is 2688, while the sum is 31.

The square root of 81182173 is about 9010.1150381113. The cubic root of 81182173 is about 432.9989972722.

The spelling of 81182173 in words is "eighty-one million, one hundred eighty-two thousand, one hundred seventy-three".