81899742538 has 16 divisors (see below), whose sum is σ = 131643247680. Its totient is φ = 38076703936.

The previous prime is 81899742523. The next prime is 81899742563. The reversal of 81899742538 is 83524799818.

It is a self number, because there is not a number n which added to its sum of digits gives 81899742538.

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 7 ways as a sum of consecutive naturals, for example, 14508118 + ... + 14513761.

It is an arithmetic number, because the mean of its divisors is an integer number (8227702980).

Almost surely, 2^81899742538 is an apocalyptic number.

81899742538 is a deficient number, since it is larger than the sum of its proper divisors (49743505142).

81899742538 is a wasteful number, since it uses less digits than its factorization.

81899742538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29021981.

The product of its digits is 34836480, while the sum is 64.

The spelling of 81899742538 in words is "eighty-one billion, eight hundred ninety-nine million, seven hundred forty-two thousand, five hundred thirty-eight".