81079891793 has 2 divisors, whose sum is σ = 81079891794. Its totient is φ = 81079891792.

The previous prime is 81079891769. The next prime is 81079891853. The reversal of 81079891793 is 39719897018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79813030144 + 1266861649 = 282512^2 + 35593^2 .

It is a cyclic number.

It is not a de Polignac number, because 81079891793 - 2¹² = 81079887697 is a prime.

It is not a weakly prime, because it can be changed into another prime (81079891093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40539945896 + 40539945897.

It is an arithmetic number, because the mean of its divisors is an integer number (40539945897).

Almost surely, 2^81079891793 is an apocalyptic number.

It is an amenable number.

81079891793 is a deficient number, since it is larger than the sum of its proper divisors (1).

81079891793 is an equidigital number, since it uses as much as digits as its factorization.

81079891793 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6858432, while the sum is 62.

The spelling of 81079891793 in words is "eighty-one billion, seventy-nine million, eight hundred ninety-one thousand, seven hundred ninety-three".