18400055 has 4 divisors (see below), whose sum is σ = 22080072. Its totient is φ = 14720040.

The previous prime is 18400051. The next prime is 18400061. The reversal of 18400055 is 55000481.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 18400055 - 2² = 18400051 is a prime.

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 18400055.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18400051) 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, 1840001 + ... + 1840010.

It is an arithmetic number, because the mean of its divisors is an integer number (5520018).

Almost surely, 2^18400055 is an apocalyptic number.

18400055 is a deficient number, since it is larger than the sum of its proper divisors (3680017).

18400055 is an equidigital number, since it uses as much as digits as its factorization.

18400055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3680016.

The product of its (nonzero) digits is 800, while the sum is 23.

The square root of 18400055 is about 4289.5285288712. The cubic root of 18400055 is about 264.0014874036.

The spelling of 18400055 in words is "eighteen million, four hundred thousand, fifty-five".