81732920993 has 4 divisors (see below), whose sum is σ = 83471919360. Its totient is φ = 79993922628.

The previous prime is 81732920953. The next prime is 81732921007. The reversal of 81732920993 is 39902923718.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81732920993 - 2²⁴ = 81716143777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81732920923) 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, 869499113 + ... + 869499206.

It is an arithmetic number, because the mean of its divisors is an integer number (20867979840).

Almost surely, 2^81732920993 is an apocalyptic number.

It is an amenable number.

81732920993 is a deficient number, since it is larger than the sum of its proper divisors (1738998367).

81732920993 is a wasteful number, since it uses less digits than its factorization.

81732920993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1738998366.

The product of its (nonzero) digits is 1469664, while the sum is 53.

The spelling of 81732920993 in words is "eighty-one billion, seven hundred thirty-two million, nine hundred twenty thousand, nine hundred ninety-three".