81864808 has 16 divisors (see below), whose sum is σ = 154137060. Its totient is φ = 40761600.

The previous prime is 81864803. The next prime is 81864817. The reversal of 81864808 is 80846818.

It can be written as a sum of positive squares in 2 ways, for example, as 63011844 + 18852964 = 7938^2 + 4342^2 .

It is not an unprimeable number, because it can be changed into a prime (81864803) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19303 + ... + 23158.

Almost surely, 2^81864808 is an apocalyptic number.

It is an amenable number.

81864808 is a deficient number, since it is larger than the sum of its proper divisors (72272252).

81864808 is a wasteful number, since it uses less digits than its factorization.

81864808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42708 (or 42704 counting only the distinct ones).

The product of its (nonzero) digits is 98304, while the sum is 43.

The square root of 81864808 is about 9047.9173294190. The cubic root of 81864808 is about 434.2092614973.

The spelling of 81864808 in words is "eighty-one million, eight hundred sixty-four thousand, eight hundred eight".