19816818 has 32 divisors (see below), whose sum is σ = 45542400. Its totient is φ = 5631120.

The previous prime is 19816807. The next prime is 19816837. The reversal of 19816818 is 81861891.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 19816818.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7173 + ... + 9543.

It is an arithmetic number, because the mean of its divisors is an integer number (1423200).

Almost surely, 2^19816818 is an apocalyptic number.

19816818 is an abundant number, since it is smaller than the sum of its proper divisors (25725582).

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

19816818 is a wasteful number, since it uses less digits than its factorization.

19816818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2582.

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

The square root of 19816818 is about 4451.6084733498. The cubic root of 19816818 is about 270.6104978477.

The spelling of 19816818 in words is "nineteen million, eight hundred sixteen thousand, eight hundred eighteen".