81637168 has 10 divisors (see below), whose sum is σ = 158172044. Its totient is φ = 40818576.

The previous prime is 81637159. The next prime is 81637169. The reversal of 81637168 is 86173618.

It is a self number, because there is not a number n which added to its sum of digits gives 81637168.

It is not an unprimeable number, because it can be changed into a prime (81637169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2551146 + ... + 2551177.

Almost surely, 2^81637168 is an apocalyptic number.

It is an amenable number.

81637168 is a deficient number, since it is larger than the sum of its proper divisors (76534876).

81637168 is a wasteful number, since it uses less digits than its factorization.

81637168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5102331 (or 5102325 counting only the distinct ones).

The product of its digits is 48384, while the sum is 40.

The square root of 81637168 is about 9035.3288816733. The cubic root of 81637168 is about 433.8064219140.

The spelling of 81637168 in words is "eighty-one million, six hundred thirty-seven thousand, one hundred sixty-eight".