18219818 has 24 divisors (see below), whose sum is σ = 30280068. Its totient is φ = 8193152.

The previous prime is 18219809. The next prime is 18219821. The reversal of 18219818 is 81891281.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17330569 + 889249 = 4163^2 + 943^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17480 + ... + 18492.

Almost surely, 2^18219818 is an apocalyptic number.

18219818 is a deficient number, since it is larger than the sum of its proper divisors (12060250).

18219818 is a wasteful number, since it uses less digits than its factorization.

18219818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1078 (or 1055 counting only the distinct ones).

The product of its digits is 9216, while the sum is 38.

The square root of 18219818 is about 4268.4678750109. The cubic root of 18219818 is about 263.1366520832.

The spelling of 18219818 in words is "eighteen million, two hundred nineteen thousand, eight hundred eighteen".