81859759 has 4 divisors (see below), whose sum is σ = 83601504. Its totient is φ = 80118016.

The previous prime is 81859753. The next prime is 81859787. The reversal of 81859759 is 95795818.

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 81859759 - 2¹⁵ = 81826991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81859753) 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 3 ways as a sum of consecutive naturals, for example, 870802 + ... + 870895.

It is an arithmetic number, because the mean of its divisors is an integer number (20900376).

Almost surely, 2^81859759 is an apocalyptic number.

81859759 is a deficient number, since it is larger than the sum of its proper divisors (1741745).

81859759 is a wasteful number, since it uses less digits than its factorization.

81859759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1741744.

The product of its digits is 907200, while the sum is 52.

The square root of 81859759 is about 9047.6383106311. The cubic root of 81859759 is about 434.2003347163.

The spelling of 81859759 in words is "eighty-one million, eight hundred fifty-nine thousand, seven hundred fifty-nine".