18640018 has 4 divisors (see below), whose sum is σ = 27960030. Its totient is φ = 9320008.

The previous prime is 18640009. The next prime is 18640019. The reversal of 18640018 is 81004681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81004681 = 71 ⋅1140911.

It can be written as a sum of positive squares in only one way, i.e., 16184529 + 2455489 = 4023^2 + 1567^2 .

It is not an unprimeable number, because it can be changed into a prime (18640019) 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, 4660003 + ... + 4660006.

Almost surely, 2^18640018 is an apocalyptic number.

18640018 is a deficient number, since it is larger than the sum of its proper divisors (9320012).

18640018 is an equidigital number, since it uses as much as digits as its factorization.

18640018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9320011.

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 18640018 is about 4317.4087135688. The cubic root of 18640018 is about 265.1441863969.

Adding to 18640018 its reverse (81004681), we get a palindrome (99644699).

It can be divided in two parts, 186 and 40018, that added together give a palindrome (40204).

The spelling of 18640018 in words is "eighteen million, six hundred forty thousand, eighteen".