18238666 has 4 divisors (see below), whose sum is σ = 27358002. Its totient is φ = 9119332.

The previous prime is 18238663. The next prime is 18238687. The reversal of 18238666 is 66683281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66683281 = 7 ⋅9526183.

It can be written as a sum of positive squares in only one way, i.e., 10791225 + 7447441 = 3285^2 + 2729^2 .

It is not an unprimeable number, because it can be changed into a prime (18238663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4559665 + ... + 4559668.

Almost surely, 2^18238666 is an apocalyptic number.

18238666 is a deficient number, since it is larger than the sum of its proper divisors (9119336).

18238666 is an equidigital number, since it uses as much as digits as its factorization.

18238666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9119335.

The product of its digits is 82944, while the sum is 40.

The square root of 18238666 is about 4270.6751222728. The cubic root of 18238666 is about 263.2273571678.

The spelling of 18238666 in words is "eighteen million, two hundred thirty-eight thousand, six hundred sixty-six".