81919683819 has 12 divisors (see below), whose sum is σ = 118338854400. Its totient is φ = 54608312304.

The previous prime is 81919683779. The next prime is 81919683841. The reversal of 81919683819 is 91838691918.

81919683819 is a `hidden beast` number, since 8 + 191 + 9 + 68 + 381 + 9 = 666.

It is not a de Polignac number, because 81919683819 - 2²⁰ = 81918635243 is a prime.

It is a super-2 number, since 2×81919683819² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81919688819) 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 11 ways as a sum of consecutive naturals, for example, 291424 + ... + 498765.

It is an arithmetic number, because the mean of its divisors is an integer number (9861571200).

Almost surely, 2^81919683819 is an apocalyptic number.

81919683819 is a deficient number, since it is larger than the sum of its proper divisors (36419170581).

81919683819 is a wasteful number, since it uses less digits than its factorization.

81919683819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801714 (or 801711 counting only the distinct ones).

The product of its digits is 6718464, while the sum is 63.

The spelling of 81919683819 in words is "eighty-one billion, nine hundred nineteen million, six hundred eighty-three thousand, eight hundred nineteen".