81399868 has 24 divisors (see below), whose sum is σ = 160760880. Its totient is φ = 35723520.

The previous prime is 81399847. The next prime is 81399887. The reversal of 81399868 is 86899318.

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 in 7 ways as a sum of consecutive naturals, for example, 30621 + ... + 33172.

It is an arithmetic number, because the mean of its divisors is an integer number (6698370).

Almost surely, 2^81399868 is an apocalyptic number.

It is an amenable number.

81399868 is a deficient number, since it is larger than the sum of its proper divisors (79361012).

81399868 is a wasteful number, since it uses less digits than its factorization.

81399868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63837 (or 63835 counting only the distinct ones).

The product of its digits is 746496, while the sum is 52.

The square root of 81399868 is about 9022.1875396159. The cubic root of 81399868 is about 433.3856896634.

The spelling of 81399868 in words is "eighty-one million, three hundred ninety-nine thousand, eight hundred sixty-eight".