81918512 has 40 divisors (see below), whose sum is σ = 180988416. Its totient is φ = 35582976.

The previous prime is 81918511. The next prime is 81918521. The reversal of 81918512 is 21581918.

It is not an unprimeable number, because it can be changed into a prime (81918511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8048 + ... + 15119.

Almost surely, 2^81918512 is an apocalyptic number.

It is an amenable number.

81918512 is an abundant number, since it is smaller than the sum of its proper divisors (99069904).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81918512 is a wasteful number, since it uses less digits than its factorization.

81918512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23205 (or 23199 counting only the distinct ones).

The product of its digits is 5760, while the sum is 35.

The square root of 81918512 is about 9050.8845976512. The cubic root of 81918512 is about 434.3041890472.

The spelling of 81918512 in words is "eighty-one million, nine hundred eighteen thousand, five hundred twelve".