81634740640 has 48 divisors (see below), whose sum is σ = 192937489920. Its totient is φ = 32641127680.

The previous prime is 81634740637. The next prime is 81634740667. The reversal of 81634740640 is 4604743618.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 316101 + ... + 513019.

It is an arithmetic number, because the mean of its divisors is an integer number (4019531040).

Almost surely, 2^81634740640 is an apocalyptic number.

81634740640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81634740640 is an abundant number, since it is smaller than the sum of its proper divisors (111302749280).

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

81634740640 is a wasteful number, since it uses less digits than its factorization.

81634740640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199525 (or 199517 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 43.

The spelling of 81634740640 in words is "eighty-one billion, six hundred thirty-four million, seven hundred forty thousand, six hundred forty".