81789916 has 48 divisors (see below), whose sum is σ = 159536160. Its totient is φ = 36666240.

The previous prime is 81789899. The next prime is 81789919. The reversal of 81789916 is 61998718.

It is a self number, because there is not a number n which added to its sum of digits gives 81789916.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81789919) 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 15 ways as a sum of consecutive naturals, for example, 360195 + ... + 360421.

It is an arithmetic number, because the mean of its divisors is an integer number (3323670).

Almost surely, 2^81789916 is an apocalyptic number.

It is an amenable number.

81789916 is a deficient number, since it is larger than the sum of its proper divisors (77746244).

81789916 is a wasteful number, since it uses less digits than its factorization.

81789916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311 (or 283 counting only the distinct ones).

The product of its digits is 217728, while the sum is 49.

The square root of 81789916 is about 9043.7777504757. Note that the first 4 decimals coincide. The cubic root of 81789916 is about 434.0768125562.

The spelling of 81789916 in words is "eighty-one million, seven hundred eighty-nine thousand, nine hundred sixteen".