81217170 has 24 divisors (see below), whose sum is σ = 211164876. Its totient is φ = 21657888.

The previous prime is 81217151. The next prime is 81217237. The reversal of 81217170 is 7171218.

It can be written as a sum of positive squares in 2 ways, for example, as 77633721 + 3583449 = 8811^2 + 1893^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 451117 + ... + 451296.

Almost surely, 2^81217170 is an apocalyptic number.

81217170 is an abundant number, since it is smaller than the sum of its proper divisors (129947706).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81217170 is a wasteful number, since it uses less digits than its factorization.

81217170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 902426 (or 902423 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 27.

The square root of 81217170 is about 9012.0569239214. The cubic root of 81217170 is about 433.0612091607.

Adding to 81217170 its reverse (7171218), we get a palindrome (88388388).

The spelling of 81217170 in words is "eighty-one million, two hundred seventeen thousand, one hundred seventy".