81861708 has 12 divisors (see below), whose sum is σ = 191010680. Its totient is φ = 27287232.

The previous prime is 81861691. The next prime is 81861727. The reversal of 81861708 is 80716818.

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

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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, 3410893 + ... + 3410916.

Almost surely, 2^81861708 is an apocalyptic number.

It is an amenable number.

81861708 is an abundant number, since it is smaller than the sum of its proper divisors (109148972).

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

81861708 is a wasteful number, since it uses less digits than its factorization.

81861708 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6821816 (or 6821814 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 39.

The square root of 81861708 is about 9047.7460176554. The cubic root of 81861708 is about 434.2037806493.

It can be divided in two parts, 818 and 61708, that added together give a palindrome (62526).

The spelling of 81861708 in words is "eighty-one million, eight hundred sixty-one thousand, seven hundred eight".