81440664650 has 48 divisors (see below), whose sum is σ = 152607280128. Its totient is φ = 32334120000.

The previous prime is 81440664647. The next prime is 81440664671. The reversal of 81440664650 is 5646604418.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11102384 + ... + 11109716.

It is an arithmetic number, because the mean of its divisors is an integer number (3179318336).

Almost surely, 2^81440664650 is an apocalyptic number.

81440664650 is a deficient number, since it is larger than the sum of its proper divisors (71166615478).

81440664650 is a wasteful number, since it uses less digits than its factorization.

81440664650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8967 (or 8962 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 44.

The spelling of 81440664650 in words is "eighty-one billion, four hundred forty million, six hundred sixty-four thousand, six hundred fifty".