81943719693 has 16 divisors (see below), whose sum is σ = 120245656896. Its totient is φ = 49223363840.

The previous prime is 81943719691. The next prime is 81943719713. The reversal of 81943719693 is 39691734918.

It is a cyclic number.

It is not a de Polignac number, because 81943719693 - 2¹ = 81943719691 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81943719691) 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 15 ways as a sum of consecutive naturals, for example, 10983630 + ... + 10991087.

It is an arithmetic number, because the mean of its divisors is an integer number (7515353556).

Almost surely, 2^81943719693 is an apocalyptic number.

It is an amenable number.

81943719693 is a deficient number, since it is larger than the sum of its proper divisors (38301937203).

81943719693 is a wasteful number, since it uses less digits than its factorization.

81943719693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21974844.

The product of its digits is 8817984, while the sum is 60.

The spelling of 81943719693 in words is "eighty-one billion, nine hundred forty-three million, seven hundred nineteen thousand, six hundred ninety-three".