81686609944 has 16 divisors (see below), whose sum is σ = 153476902800. Its totient is φ = 40759435872.

The previous prime is 81686609887. The next prime is 81686609987. The reversal of 81686609944 is 44990668618.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10479499 + ... + 10487290.

It is an arithmetic number, because the mean of its divisors is an integer number (9592306425).

Almost surely, 2^81686609944 is an apocalyptic number.

It is an amenable number.

81686609944 is a deficient number, since it is larger than the sum of its proper divisors (71790292856).

81686609944 is a wasteful number, since it uses less digits than its factorization.

81686609944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20967282 (or 20967278 counting only the distinct ones).

The product of its (nonzero) digits is 17915904, while the sum is 61.

The spelling of 81686609944 in words is "eighty-one billion, six hundred eighty-six million, six hundred nine thousand, nine hundred forty-four".