81799871 has 4 divisors (see below), whose sum is σ = 82341744. Its totient is φ = 81258000.

The previous prime is 81799853. The next prime is 81799877. The reversal of 81799871 is 17899718.

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 81799871 - 2²⁶ = 14691007 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 (81799877) 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, 270710 + ... + 271011.

It is an arithmetic number, because the mean of its divisors is an integer number (20585436).

Almost surely, 2^81799871 is an apocalyptic number.

81799871 is a deficient number, since it is larger than the sum of its proper divisors (541873).

81799871 is a wasteful number, since it uses less digits than its factorization.

81799871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541872.

The product of its digits is 254016, while the sum is 50.

The square root of 81799871 is about 9044.3281121375. The cubic root of 81799871 is about 434.0944229560.

The spelling of 81799871 in words is "eighty-one million, seven hundred ninety-nine thousand, eight hundred seventy-one".