81985818 has 8 divisors (see below), whose sum is σ = 163971648. Its totient is φ = 27328604.

The previous prime is 81985807. The next prime is 81985819. The reversal of 81985818 is 81858918.

It is a sphenic number, since it is the product of 3 distinct primes.

81985818 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (81985819) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6832146 + ... + 6832157.

It is an arithmetic number, because the mean of its divisors is an integer number (20496456).

Almost surely, 2^81985818 is an apocalyptic number.

81985818 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81985818 is a wasteful number, since it uses less digits than its factorization.

81985818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13664308.

The product of its digits is 184320, while the sum is 48.

The square root of 81985818 is about 9054.6020343249. The cubic root of 81985818 is about 434.4231010204.

The spelling of 81985818 in words is "eighty-one million, nine hundred eighty-five thousand, eight hundred eighteen".