81735474640 has 20 divisors (see below), whose sum is σ = 190034978724. Its totient is φ = 32694189824.

The previous prime is 81735474637. The next prime is 81735474659. The reversal of 81735474640 is 4647453718.

It can be written as a sum of positive squares in 2 ways, for example, as 37875387456 + 43860087184 = 194616^2 + 209428^2 .

It is a tau number, because it is divible by the number of its divisors (20).

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 3 ways as a sum of consecutive naturals, for example, 510846637 + ... + 510846796.

Almost surely, 2^81735474640 is an apocalyptic number.

81735474640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81735474640 is an abundant number, since it is smaller than the sum of its proper divisors (108299504084).

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

81735474640 is a wasteful number, since it uses less digits than its factorization.

81735474640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1021693446 (or 1021693440 counting only the distinct ones).

The product of its (nonzero) digits is 2257920, while the sum is 49.

The spelling of 81735474640 in words is "eighty-one billion, seven hundred thirty-five million, four hundred seventy-four thousand, six hundred forty".