18243891 has 6 divisors (see below), whose sum is σ = 26352300. Its totient is φ = 12162588.

The previous prime is 18243881. The next prime is 18243913. The reversal of 18243891 is 19834281.

It is not a de Polignac number, because 18243891 - 2²² = 14049587 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18243851) 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 5 ways as a sum of consecutive naturals, for example, 1013541 + ... + 1013558.

It is an arithmetic number, because the mean of its divisors is an integer number (4392050).

Almost surely, 2^18243891 is an apocalyptic number.

18243891 is a deficient number, since it is larger than the sum of its proper divisors (8108409).

18243891 is a wasteful number, since it uses less digits than its factorization.

18243891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2027105 (or 2027102 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 18243891 is about 4271.2868084454. The cubic root of 18243891 is about 263.2524911629.

The spelling of 18243891 in words is "eighteen million, two hundred forty-three thousand, eight hundred ninety-one".