81799699819 has 4 divisors (see below), whose sum is σ = 81802564696. Its totient is φ = 81796834944.

The previous prime is 81799699771. The next prime is 81799699823. The reversal of 81799699819 is 91899699718.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 91899699718 = 2 ⋅45949849859.

It is a cyclic number.

It is not a de Polignac number, because 81799699819 - 2³⁵ = 47439961451 is a prime.

It is a super-2 number, since 2×81799699819² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81799699889) 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 3 ways as a sum of consecutive naturals, for example, 1389174 + ... + 1446859.

It is an arithmetic number, because the mean of its divisors is an integer number (20450641174).

Almost surely, 2^81799699819 is an apocalyptic number.

81799699819 is a deficient number, since it is larger than the sum of its proper divisors (2864877).

81799699819 is a wasteful number, since it uses less digits than its factorization.

81799699819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2864876.

The product of its digits is 158723712, while the sum is 76.

The spelling of 81799699819 in words is "eighty-one billion, seven hundred ninety-nine million, six hundred ninety-nine thousand, eight hundred nineteen".