81513171 has 12 divisors (see below), whose sum is σ = 121801680. Its totient is φ = 52468080.

The previous prime is 81513151. The next prime is 81513191. The reversal of 81513171 is 17131518.

81513171 is a `hidden beast` number, since 81 + 513 + 1 + 71 = 666.

It is an interprime number because it is at equal distance from previous prime (81513151) and next prime (81513191).

It is not a de Polignac number, because 81513171 - 2⁵ = 81513139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81513121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 155895 + ... + 156416.

It is an arithmetic number, because the mean of its divisors is an integer number (10150140).

Almost surely, 2^81513171 is an apocalyptic number.

81513171 is a deficient number, since it is larger than the sum of its proper divisors (40288509).

81513171 is a wasteful number, since it uses less digits than its factorization.

81513171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312346 (or 312343 counting only the distinct ones).

The product of its digits is 840, while the sum is 27.

The square root of 81513171 is about 9028.4644873865. The cubic root of 81513171 is about 433.5866774313.

Adding to 81513171 its reverse (17131518), we get a palindrome (98644689).

The spelling of 81513171 in words is "eighty-one million, five hundred thirteen thousand, one hundred seventy-one".