18037891 has 4 divisors (see below), whose sum is σ = 18167800. Its totient is φ = 17907984.

The previous prime is 18037889. The next prime is 18037919. The reversal of 18037891 is 19873081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19873081 = 23 ⋅864047.

It is a cyclic number.

It is not a de Polignac number, because 18037891 - 2¹ = 18037889 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 18037891.

It is not an unprimeable number, because it can be changed into a prime (18037841) 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 3 ways as a sum of consecutive naturals, for example, 64746 + ... + 65023.

It is an arithmetic number, because the mean of its divisors is an integer number (4541950).

Almost surely, 2^18037891 is an apocalyptic number.

18037891 is a deficient number, since it is larger than the sum of its proper divisors (129909).

18037891 is a wasteful number, since it uses less digits than its factorization.

18037891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129908.

The product of its (nonzero) digits is 12096, while the sum is 37.

The square root of 18037891 is about 4247.1038367339. The cubic root of 18037891 is about 262.2579040773.

The spelling of 18037891 in words is "eighteen million, thirty-seven thousand, eight hundred ninety-one".