81394864 has 10 divisors (see below), whose sum is σ = 157702580. Its totient is φ = 40697424.

The previous prime is 81394853. The next prime is 81394867. The reversal of 81394864 is 46849318.

It is a self number, because there is not a number n which added to its sum of digits gives 81394864.

It is not an unprimeable number, because it can be changed into a prime (81394867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2543574 + ... + 2543605.

It is an arithmetic number, because the mean of its divisors is an integer number (15770258).

Almost surely, 2^81394864 is an apocalyptic number.

It is an amenable number.

81394864 is a deficient number, since it is larger than the sum of its proper divisors (76307716).

81394864 is a wasteful number, since it uses less digits than its factorization.

81394864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5087187 (or 5087181 counting only the distinct ones).

The product of its digits is 165888, while the sum is 43.

The square root of 81394864 is about 9021.9102190168. The cubic root of 81394864 is about 433.3768087873.

The spelling of 81394864 in words is "eighty-one million, three hundred ninety-four thousand, eight hundred sixty-four".