81696387859 has 4 divisors (see below), whose sum is σ = 81748128760. Its totient is φ = 81644646960.

The previous prime is 81696387847. The next prime is 81696387887. The reversal of 81696387859 is 95878369618.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81696387859 - 2¹¹ = 81696385811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81696387889) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25868082 + ... + 25871239.

It is an arithmetic number, because the mean of its divisors is an integer number (20437032190).

Almost surely, 2^81696387859 is an apocalyptic number.

81696387859 is a deficient number, since it is larger than the sum of its proper divisors (51740901).

81696387859 is a wasteful number, since it uses less digits than its factorization.

81696387859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51740900.

The product of its digits is 156764160, while the sum is 70.

The spelling of 81696387859 in words is "eighty-one billion, six hundred ninety-six million, three hundred eighty-seven thousand, eight hundred fifty-nine".