18199988 has 18 divisors (see below), whose sum is σ = 32562054. Its totient is φ = 8897824.

The previous prime is 18199963. The next prime is 18199999. The reversal of 18199988 is 88999181.

It can be written as a sum of positive squares in 3 ways, for example, as 13823524 + 4376464 = 3718^2 + 2092^2 .

It is a Harshad number since it is a multiple of its sum of digits (53).

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 5 ways as a sum of consecutive naturals, for example, 61970 + ... + 62262.

It is an arithmetic number, because the mean of its divisors is an integer number (1809003).

Almost surely, 2^18199988 is an apocalyptic number.

It is an amenable number.

18199988 is a deficient number, since it is larger than the sum of its proper divisors (14362066).

18199988 is an equidigital number, since it uses as much as digits as its factorization.

18199988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 643 (or 348 counting only the distinct ones).

The product of its digits is 373248, while the sum is 53.

The square root of 18199988 is about 4266.1443951184. The cubic root of 18199988 is about 263.0411536173.

Multiplying 18199988 by its sum of digits (53), we get a square (964599364 = 31058²).

18199988 divided by its sum of digits (53) gives a square (343396 = 586²).

The spelling of 18199988 in words is "eighteen million, one hundred ninety-nine thousand, nine hundred eighty-eight".