81812855 has 4 divisors (see below), whose sum is σ = 98175432. Its totient is φ = 65450280.

The previous prime is 81812839. The next prime is 81812897. The reversal of 81812855 is 55821818.

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

It is not a de Polignac number, because 81812855 - 2⁴ = 81812839 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8181281 + ... + 8181290.

It is an arithmetic number, because the mean of its divisors is an integer number (24543858).

Almost surely, 2^81812855 is an apocalyptic number.

81812855 is a deficient number, since it is larger than the sum of its proper divisors (16362577).

81812855 is a wasteful number, since it uses less digits than its factorization.

81812855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16362576.

The product of its digits is 25600, while the sum is 38.

The square root of 81812855 is about 9045.0458815862. The cubic root of 81812855 is about 434.1173895114.

The spelling of 81812855 in words is "eighty-one million, eight hundred twelve thousand, eight hundred fifty-five".