18681816 has 16 divisors (see below), whose sum is σ = 46704600. Its totient is φ = 6227264.

The previous prime is 18681797. The next prime is 18681833. The reversal of 18681816 is 61818681.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 389181 + ... + 389228.

Almost surely, 2^18681816 is an apocalyptic number.

It is an amenable number.

18681816 is an abundant number, since it is smaller than the sum of its proper divisors (28022784).

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

18681816 is a wasteful number, since it uses less digits than its factorization.

18681816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778418 (or 778414 counting only the distinct ones).

The product of its digits is 18432, while the sum is 39.

The square root of 18681816 is about 4322.2466380344. The cubic root of 18681816 is about 265.3422231028.

The spelling of 18681816 in words is "eighteen million, six hundred eighty-one thousand, eight hundred sixteen".