81259139187738 has 16 divisors (see below), whose sum is σ = 180575864861760. Its totient is φ = 27086379729228.

The previous prime is 81259139187701. The next prime is 81259139187749. The reversal of 81259139187738 is 83778193195218.

81259139187738 is a `hidden beast` number, since 8 + 1 + 2 + 5 + 91 + 391 + 87 + 73 + 8 = 666.

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, 752399436870 + ... + 752399436977.

It is an arithmetic number, because the mean of its divisors is an integer number (11285991553860).

Almost surely, 2^{81259139187738} is an apocalyptic number.

81259139187738 is an abundant number, since it is smaller than the sum of its proper divisors (99316725674022).

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

81259139187738 is a wasteful number, since it uses less digits than its factorization.

81259139187738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1504798873858 (or 1504798873852 counting only the distinct ones).

The product of its digits is 182891520, while the sum is 72.

The spelling of 81259139187738 in words is "eighty-one trillion, two hundred fifty-nine billion, one hundred thirty-nine million, one hundred eighty-seven thousand, seven hundred thirty-eight".