81366648390 has 64 divisors (see below), whose sum is σ = 217633489920. Its totient is φ = 21632196960.

The previous prime is 81366648379. The next prime is 81366648427. The reversal of 81366648390 is 9384666318.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 365854 + ... + 544593.

It is an arithmetic number, because the mean of its divisors is an integer number (3400523280).

Almost surely, 2^81366648390 is an apocalyptic number.

81366648390 is an abundant number, since it is smaller than the sum of its proper divisors (136266841530).

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

81366648390 is a wasteful number, since it uses less digits than its factorization.

81366648390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 910794 (or 910788 counting only the distinct ones).

The product of its (nonzero) digits is 4478976, while the sum is 54.

The spelling of 81366648390 in words is "eighty-one billion, three hundred sixty-six million, six hundred forty-eight thousand, three hundred ninety".