18001855 has 8 divisors (see below), whose sum is σ = 22299264. Its totient is φ = 13936800.

The previous prime is 18001853. The next prime is 18001859. The reversal of 18001855 is 55810081.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18001855 - 2¹ = 18001853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18001853) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57916 + ... + 58225.

It is an arithmetic number, because the mean of its divisors is an integer number (2787408).

Almost surely, 2^18001855 is an apocalyptic number.

18001855 is a deficient number, since it is larger than the sum of its proper divisors (4297409).

18001855 is a wasteful number, since it uses less digits than its factorization.

18001855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116177.

The product of its (nonzero) digits is 1600, while the sum is 28.

The square root of 18001855 is about 4242.8592953337. The cubic root of 18001855 is about 262.0831418437.

It can be divided in two parts, 1800 and 1855, that added together give a triangular number (3655 = T₈₅).

The spelling of 18001855 in words is "eighteen million, one thousand, eight hundred fifty-five".