18381855 has 16 divisors (see below), whose sum is σ = 30096000. Its totient is φ = 9575328.

The previous prime is 18381833. The next prime is 18381871. The reversal of 18381855 is 55818381.

It is not a de Polignac number, because 18381855 - 2⁹ = 18381343 is a prime.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 13605 + ... + 14894.

It is an arithmetic number, because the mean of its divisors is an integer number (1881000).

Almost surely, 2^18381855 is an apocalyptic number.

18381855 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

18381855 is a deficient number, since it is larger than the sum of its proper divisors (11714145).

18381855 is a wasteful number, since it uses less digits than its factorization.

18381855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28550.

The product of its digits is 38400, while the sum is 39.

The square root of 18381855 is about 4287.4065587485. The cubic root of 18381855 is about 263.9144149802.

The spelling of 18381855 in words is "eighteen million, three hundred eighty-one thousand, eight hundred fifty-five".