18691818 has 16 divisors (see below), whose sum is σ = 38295936. Its totient is φ = 6078560.

The previous prime is 18691811. The next prime is 18691819. The reversal of 18691818 is 81819681.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 18691818.

It is not an unprimeable number, because it can be changed into a prime (18691811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37746 + ... + 38237.

It is an arithmetic number, because the mean of its divisors is an integer number (2393496).

Almost surely, 2^18691818 is an apocalyptic number.

18691818 is an abundant number, since it is smaller than the sum of its proper divisors (19604118).

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

18691818 is a wasteful number, since it uses less digits than its factorization.

18691818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76029.

The product of its digits is 27648, while the sum is 42.

The square root of 18691818 is about 4323.4035203760. The cubic root of 18691818 is about 265.3895682400.

The spelling of 18691818 in words is "eighteen million, six hundred ninety-one thousand, eight hundred eighteen".