81691919116 has 48 divisors (see below), whose sum is σ = 145006202880. Its totient is φ = 40266720000.

The previous prime is 81691919047. The next prime is 81691919131. The reversal of 81691919116 is 61191919618.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68019316 + ... + 68020516.

It is an arithmetic number, because the mean of its divisors is an integer number (3020962560).

Almost surely, 2^81691919116 is an apocalyptic number.

It is an amenable number.

81691919116 is a deficient number, since it is larger than the sum of its proper divisors (63314283764).

81691919116 is a wasteful number, since it uses less digits than its factorization.

81691919116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2086 (or 2084 counting only the distinct ones).

The product of its digits is 209952, while the sum is 52.

The spelling of 81691919116 in words is "eighty-one billion, six hundred ninety-one million, nine hundred nineteen thousand, one hundred sixteen".