81855371 has 12 divisors (see below), whose sum is σ = 91308672. Its totient is φ = 72943584.

The previous prime is 81855337. The next prime is 81855377. The reversal of 81855371 is 17355818.

It is a de Polignac number, because none of the positive numbers 2^k-81855371 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81855377) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7190 + ... + 14676.

It is an arithmetic number, because the mean of its divisors is an integer number (7609056).

Almost surely, 2^81855371 is an apocalyptic number.

81855371 is a deficient number, since it is larger than the sum of its proper divisors (9453301).

81855371 is a wasteful number, since it uses less digits than its factorization.

81855371 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7558 (or 7529 counting only the distinct ones).

The product of its digits is 33600, while the sum is 38.

The square root of 81855371 is about 9047.3958131608. The cubic root of 81855371 is about 434.1925763047.

The spelling of 81855371 in words is "eighty-one million, eight hundred fifty-five thousand, three hundred seventy-one".