81691381422 has 48 divisors (see below), whose sum is σ = 202604193792. Its totient is φ = 23303382480.

The previous prime is 81691381403. The next prime is 81691381433. The reversal of 81691381422 is 22418319618.

81691381422 is a `hidden beast` number, since 81 + 69 + 13 + 81 + 422 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 434238 + ... + 593249.

It is an arithmetic number, because the mean of its divisors is an integer number (4220920704).

Almost surely, 2^81691381422 is an apocalyptic number.

81691381422 is an abundant number, since it is smaller than the sum of its proper divisors (120912812370).

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

81691381422 is a wasteful number, since it uses less digits than its factorization.

81691381422 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1028133 (or 1028130 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The spelling of 81691381422 in words is "eighty-one billion, six hundred ninety-one million, three hundred eighty-one thousand, four hundred twenty-two".