18055891 has 8 divisors (see below), whose sum is σ = 20666880. Its totient is φ = 15452808.

The previous prime is 18055879. The next prime is 18055901. The reversal of 18055891 is 19855081.

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

It is not a de Polignac number, because 18055891 - 2⁵ = 18055859 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 18055891.

It is not an unprimeable number, because it can be changed into a prime (18055801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4230 + ... + 7348.

It is an arithmetic number, because the mean of its divisors is an integer number (2583360).

Almost surely, 2^18055891 is an apocalyptic number.

18055891 is a deficient number, since it is larger than the sum of its proper divisors (2610989).

18055891 is an equidigital number, since it uses as much as digits as its factorization.

18055891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3953.

The product of its (nonzero) digits is 14400, while the sum is 37.

The square root of 18055891 is about 4249.2223994515. Note that the first 3 decimals coincide. The cubic root of 18055891 is about 262.3451107413.

It can be divided in two parts, 180558 and 91, that multiplied together give a triangular number (16430778 = T₅₇₃₂).

The spelling of 18055891 in words is "eighteen million, fifty-five thousand, eight hundred ninety-one".