81840312 has 48 divisors (see below), whose sum is σ = 234692640. Its totient is φ = 25675008.

The previous prime is 81840289. The next prime is 81840323. The reversal of 81840312 is 21304818.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 32208 + ... + 34655.

It is an arithmetic number, because the mean of its divisors is an integer number (4889430).

Almost surely, 2^81840312 is an apocalyptic number.

It is an amenable number.

81840312 is an abundant number, since it is smaller than the sum of its proper divisors (152852328).

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

81840312 is a wasteful number, since it uses less digits than its factorization.

81840312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66892 (or 66885 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 81840312 is about 9046.5635464523. The cubic root of 81840312 is about 434.1659484165.

The spelling of 81840312 in words is "eighty-one million, eight hundred forty thousand, three hundred twelve".