18001638 has 24 divisors (see below), whose sum is σ = 40262976. Its totient is φ = 5806800.

The previous prime is 18001631. The next prime is 18001639. The reversal of 18001638 is 83610081.

18001638 is a modest number, since divided by 1638 gives 18 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18001631) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 15573 + ... + 16688.

It is an arithmetic number, because the mean of its divisors is an integer number (1677624).

Almost surely, 2^18001638 is an apocalyptic number.

18001638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

18001638 is an abundant number, since it is smaller than the sum of its proper divisors (22261338).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18001638 is a wasteful number, since it uses less digits than its factorization.

18001638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32300 (or 32297 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 18001638 is about 4242.8337228791. The cubic root of 18001638 is about 262.0820887620.

The spelling of 18001638 in words is "eighteen million, one thousand, six hundred thirty-eight".