81391126668 has 24 divisors (see below), whose sum is σ = 189917647920. Its totient is φ = 27129658560.

The previous prime is 81391126577. The next prime is 81391126703. The reversal of 81391126668 is 86662119318.

It is a self number, because there is not a number n which added to its sum of digits gives 81391126668.

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, 588738 + ... + 713718.

It is an arithmetic number, because the mean of its divisors is an integer number (7913235330).

Almost surely, 2^81391126668 is an apocalyptic number.

It is an amenable number.

81391126668 is an abundant number, since it is smaller than the sum of its proper divisors (108526521252).

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

81391126668 is a wasteful number, since it uses less digits than its factorization.

81391126668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179257 (or 179255 counting only the distinct ones).

The product of its digits is 746496, while the sum is 51.

The spelling of 81391126668 in words is "eighty-one billion, three hundred ninety-one million, one hundred twenty-six thousand, six hundred sixty-eight".