81811138208368 has 40 divisors (see below), whose sum is σ = 160923306999168. Its totient is φ = 40282910365632.

The previous prime is 81811138208363. The next prime is 81811138208369. The reversal of 81811138208368 is 86380283111818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81811138208363) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7920796 + ... + 15045307.

Almost surely, 2^{81811138208368} is an apocalyptic number.

It is an amenable number.

81811138208368 is a deficient number, since it is larger than the sum of its proper divisors (79112168790800).

81811138208368 is a wasteful number, since it uses less digits than its factorization.

81811138208368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22969501 (or 22969495 counting only the distinct ones).

The product of its (nonzero) digits is 3538944, while the sum is 58.

The spelling of 81811138208368 in words is "eighty-one trillion, eight hundred eleven billion, one hundred thirty-eight million, two hundred eight thousand, three hundred sixty-eight".