81079816191 has 16 divisors (see below), whose sum is σ = 117939103488. Its totient is φ = 49137272000.

The previous prime is 81079816183. The next prime is 81079816211. The reversal of 81079816191 is 19161897018.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81079816191 - 2³ = 81079816183 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81079811191) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1354291 + ... + 1412891.

It is an arithmetic number, because the mean of its divisors is an integer number (7371193968).

Almost surely, 2^81079816191 is an apocalyptic number.

81079816191 is a deficient number, since it is larger than the sum of its proper divisors (36859287297).

81079816191 is a wasteful number, since it uses less digits than its factorization.

81079816191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100542.

The product of its (nonzero) digits is 217728, while the sum is 51.

The spelling of 81079816191 in words is "eighty-one billion, seventy-nine million, eight hundred sixteen thousand, one hundred ninety-one".