81994606923 has 4 divisors (see below), whose sum is σ = 109326142568. Its totient is φ = 54663071280.

The previous prime is 81994606919. The next prime is 81994606957. The reversal of 81994606923 is 32960649918.

It is a happy number.

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

It is not a de Polignac number, because 81994606923 - 2² = 81994606919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81994606423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13665767818 + ... + 13665767823.

It is an arithmetic number, because the mean of its divisors is an integer number (27331535642).

Almost surely, 2^81994606923 is an apocalyptic number.

81994606923 is a deficient number, since it is larger than the sum of its proper divisors (27331535645).

81994606923 is a wasteful number, since it uses less digits than its factorization.

81994606923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27331535644.

The product of its (nonzero) digits is 5038848, while the sum is 57.

The spelling of 81994606923 in words is "eighty-one billion, nine hundred ninety-four million, six hundred six thousand, nine hundred twenty-three".