81854544638 has 16 divisors (see below), whose sum is σ = 130015930464. Its totient is φ = 38516332800.

The previous prime is 81854544581. The next prime is 81854544677. The reversal of 81854544638 is 83644545818.

It is a congruent number.

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, 299231 + ... + 503237.

It is an arithmetic number, because the mean of its divisors is an integer number (8125995654).

Almost surely, 2^81854544638 is an apocalyptic number.

81854544638 is a deficient number, since it is larger than the sum of its proper divisors (48161385826).

81854544638 is a wasteful number, since it uses less digits than its factorization.

81854544638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215827.

The product of its digits is 14745600, while the sum is 56.

The spelling of 81854544638 in words is "eighty-one billion, eight hundred fifty-four million, five hundred forty-four thousand, six hundred thirty-eight".