81584866 has 16 divisors (see below), whose sum is σ = 133843680. Its totient is φ = 36989280.

The previous prime is 81584863. The next prime is 81584869. The reversal of 81584866 is 66848518.

It is an interprime number because it is at equal distance from previous prime (81584863) and next prime (81584869).

It is not an unprimeable number, because it can be changed into a prime (81584863) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4465 + ... + 13531.

It is an arithmetic number, because the mean of its divisors is an integer number (8365230).

Almost surely, 2^81584866 is an apocalyptic number.

81584866 is a deficient number, since it is larger than the sum of its proper divisors (52258814).

81584866 is a wasteful number, since it uses less digits than its factorization.

81584866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9489.

The product of its digits is 368640, while the sum is 46.

The square root of 81584866 is about 9032.4341126852. The cubic root of 81584866 is about 433.7137607275.

The spelling of 81584866 in words is "eighty-one million, five hundred eighty-four thousand, eight hundred sixty-six".