81985894 has 4 divisors (see below), whose sum is σ = 122978844. Its totient is φ = 40992946.

The previous prime is 81985889. The next prime is 81985913. The reversal of 81985894 is 49858918.

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

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 20496472 + ... + 20496475.

It is an arithmetic number, because the mean of its divisors is an integer number (30744711).

Almost surely, 2^81985894 is an apocalyptic number.

81985894 is a deficient number, since it is larger than the sum of its proper divisors (40992950).

81985894 is a wasteful number, since it uses less digits than its factorization.

81985894 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40992949.

The product of its digits is 829440, while the sum is 52.

The square root of 81985894 is about 9054.6062310848. The cubic root of 81985894 is about 434.4232352556.

The spelling of 81985894 in words is "eighty-one million, nine hundred eighty-five thousand, eight hundred ninety-four".