81686807739 has 12 divisors (see below), whose sum is σ = 118031915976. Its totient is φ = 54439474752.

The previous prime is 81686807723. The next prime is 81686807743. The reversal of 81686807739 is 93770868618.

It is not a de Polignac number, because 81686807739 - 2⁴ = 81686807723 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81686807539) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1504942 + ... + 1558275.

It is an arithmetic number, because the mean of its divisors is an integer number (9835992998).

Almost surely, 2^81686807739 is an apocalyptic number.

81686807739 is a deficient number, since it is larger than the sum of its proper divisors (36345108237).

81686807739 is a wasteful number, since it uses less digits than its factorization.

81686807739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3066186 (or 3066183 counting only the distinct ones).

The product of its (nonzero) digits is 24385536, while the sum is 63.

The spelling of 81686807739 in words is "eighty-one billion, six hundred eighty-six million, eight hundred seven thousand, seven hundred thirty-nine".