81566372 has 12 divisors (see below), whose sum is σ = 148947456. Its totient is φ = 39009960.

The previous prime is 81566369. The next prime is 81566377. The reversal of 81566372 is 27366518.

It is not an unprimeable number, because it can be changed into a prime (81566377) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 443204 + ... + 443387.

It is an arithmetic number, because the mean of its divisors is an integer number (12412288).

Almost surely, 2^81566372 is an apocalyptic number.

It is an amenable number.

81566372 is a deficient number, since it is larger than the sum of its proper divisors (67381084).

81566372 is a wasteful number, since it uses less digits than its factorization.

81566372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 886618 (or 886616 counting only the distinct ones).

The product of its digits is 60480, while the sum is 38.

The square root of 81566372 is about 9031.4102996154. The cubic root of 81566372 is about 433.6809862321.

The spelling of 81566372 in words is "eighty-one million, five hundred sixty-six thousand, three hundred seventy-two".