81864516 has 12 divisors (see below), whose sum is σ = 191017232. Its totient is φ = 27288168.

The previous prime is 81864511. The next prime is 81864529. The reversal of 81864516 is 61546818.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (81864511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3411010 + ... + 3411033.

Almost surely, 2^81864516 is an apocalyptic number.

It is an amenable number.

81864516 is an abundant number, since it is smaller than the sum of its proper divisors (109152716).

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

81864516 is a wasteful number, since it uses less digits than its factorization.

81864516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6822050 (or 6822048 counting only the distinct ones).

The product of its digits is 46080, while the sum is 39.

The square root of 81864516 is about 9047.9011930945. The cubic root of 81864516 is about 434.2087452427.

The spelling of 81864516 in words is "eighty-one million, eight hundred sixty-four thousand, five hundred sixteen".