18188138 has 4 divisors (see below), whose sum is σ = 27282210. Its totient is φ = 9094068.

The previous prime is 18188123. The next prime is 18188167. The reversal of 18188138 is 83188181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83188181 = 137 ⋅607213.

It can be written as a sum of positive squares in only one way, i.e., 9467929 + 8720209 = 3077^2 + 2953^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4547033 + ... + 4547036.

Almost surely, 2^18188138 is an apocalyptic number.

18188138 is a deficient number, since it is larger than the sum of its proper divisors (9094072).

18188138 is an equidigital number, since it uses as much as digits as its factorization.

18188138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9094071.

The product of its digits is 12288, while the sum is 38.

The square root of 18188138 is about 4264.7553270967. The cubic root of 18188138 is about 262.9840525830.

The spelling of 18188138 in words is "eighteen million, one hundred eighty-eight thousand, one hundred thirty-eight".