18018631 has 4 divisors (see below), whose sum is σ = 18967000. Its totient is φ = 17070264.

The previous prime is 18018629. The next prime is 18018661. The reversal of 18018631 is 13681081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13681081 = 1093 ⋅12517.

It is a cyclic number.

It is not a de Polignac number, because 18018631 - 2¹ = 18018629 is a prime.

It is a super-3 number, since 3×18018631³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18018631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18018601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 474156 + ... + 474193.

It is an arithmetic number, because the mean of its divisors is an integer number (4741750).

Almost surely, 2^18018631 is an apocalyptic number.

18018631 is a deficient number, since it is larger than the sum of its proper divisors (948369).

18018631 is an equidigital number, since it uses as much as digits as its factorization.

18018631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 948368.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 18018631 is about 4244.8358036560. The cubic root of 18018631 is about 262.1645286734.

The spelling of 18018631 in words is "eighteen million, eighteen thousand, six hundred thirty-one".