81994508727 has 4 divisors (see below), whose sum is σ = 109326011640. Its totient is φ = 54663005816.

The previous prime is 81994508663. The next prime is 81994508767. The reversal of 81994508727 is 72780549918.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81994508727 - 2⁶ = 81994508663 is a prime.

It is a super-2 number, since 2×81994508727² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81994508767) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 13665751452 + ... + 13665751457.

It is an arithmetic number, because the mean of its divisors is an integer number (27331502910).

Almost surely, 2^81994508727 is an apocalyptic number.

81994508727 is a deficient number, since it is larger than the sum of its proper divisors (27331502913).

81994508727 is a wasteful number, since it uses less digits than its factorization.

81994508727 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27331502912.

The product of its (nonzero) digits is 10160640, while the sum is 60.

The spelling of 81994508727 in words is "eighty-one billion, nine hundred ninety-four million, five hundred eight thousand, seven hundred twenty-seven".