81736938993 has 4 divisors (see below), whose sum is σ = 108982585328. Its totient is φ = 54491292660.

The previous prime is 81736938979. The next prime is 81736939001. The reversal of 81736938993 is 39983963718.

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 not a de Polignac number, because 81736938993 - 2⁴ = 81736938977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81736936993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13622823163 + ... + 13622823168.

It is an arithmetic number, because the mean of its divisors is an integer number (27245646332).

Almost surely, 2^81736938993 is an apocalyptic number.

It is an amenable number.

81736938993 is a deficient number, since it is larger than the sum of its proper divisors (27245646335).

81736938993 is a wasteful number, since it uses less digits than its factorization.

81736938993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27245646334.

The product of its digits is 52907904, while the sum is 66.

The spelling of 81736938993 in words is "eighty-one billion, seven hundred thirty-six million, nine hundred thirty-eight thousand, nine hundred ninety-three".