81857659 has 8 divisors (see below), whose sum is σ = 88386480. Its totient is φ = 75362016.

The previous prime is 81857641. The next prime is 81857683. The reversal of 81857659 is 95675818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81857659 - 2⁵ = 81857627 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81857609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3037 + ... + 13150.

It is an arithmetic number, because the mean of its divisors is an integer number (11048310).

Almost surely, 2^81857659 is an apocalyptic number.

81857659 is a deficient number, since it is larger than the sum of its proper divisors (6528821).

81857659 is a wasteful number, since it uses less digits than its factorization.

81857659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16589.

The product of its digits is 604800, while the sum is 49.

The square root of 81857659 is about 9047.5222575023. The cubic root of 81857659 is about 434.1966217463.

The spelling of 81857659 in words is "eighty-one million, eight hundred fifty-seven thousand, six hundred fifty-nine".