81860840 has 32 divisors (see below), whose sum is σ = 188110080. Its totient is φ = 32046912.

The previous prime is 81860791. The next prime is 81860843. The reversal of 81860840 is 4806818.

It is a self number, because there is not a number n which added to its sum of digits gives 81860840.

It is not an unprimeable number, because it can be changed into a prime (81860843) 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 7 ways as a sum of consecutive naturals, for example, 19892 + ... + 23651.

It is an arithmetic number, because the mean of its divisors is an integer number (5878440).

Almost surely, 2^81860840 is an apocalyptic number.

It is an amenable number.

81860840 is an abundant number, since it is smaller than the sum of its proper divisors (106249240).

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

81860840 is a wasteful number, since it uses less digits than its factorization.

81860840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43601 (or 43597 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 35.

The square root of 81860840 is about 9047.6980497804. The cubic root of 81860840 is about 434.2022459871.

The spelling of 81860840 in words is "eighty-one million, eight hundred sixty thousand, eight hundred forty".