81986437864 has 32 divisors (see below), whose sum is σ = 159781497120. Its totient is φ = 39404736576.

The previous prime is 81986437861. The next prime is 81986437877. The reversal of 81986437864 is 46873468918.

It is a junction number, because it is equal to n+sod(n) for n = 81986437796 and 81986437805.

It is not an unprimeable number, because it can be changed into a prime (81986437861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1643994 + ... + 1693129.

It is an arithmetic number, because the mean of its divisors is an integer number (4993171785).

Almost surely, 2^81986437864 is an apocalyptic number.

It is an amenable number.

81986437864 is a deficient number, since it is larger than the sum of its proper divisors (77795059256).

81986437864 is a wasteful number, since it uses less digits than its factorization.

81986437864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3337249 (or 3337245 counting only the distinct ones).

The product of its digits is 55738368, while the sum is 64.

The spelling of 81986437864 in words is "eighty-one billion, nine hundred eighty-six million, four hundred thirty-seven thousand, eight hundred sixty-four".