18181943 has 4 divisors (see below), whose sum is σ = 19580568. Its totient is φ = 16783320.

The previous prime is 18181931. The next prime is 18181949. The reversal of 18181943 is 34918181.

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

It is a cyclic number.

It is not a de Polignac number, because 18181943 - 2¹⁸ = 17919799 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 (18181949) 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, 699293 + ... + 699318.

It is an arithmetic number, because the mean of its divisors is an integer number (4895142).

Almost surely, 2^18181943 is an apocalyptic number.

18181943 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

18181943 is a deficient number, since it is larger than the sum of its proper divisors (1398625).

18181943 is a wasteful number, since it uses less digits than its factorization.

18181943 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1398624.

The product of its digits is 6912, while the sum is 35.

The square root of 18181943 is about 4264.0289633163. The cubic root of 18181943 is about 262.9541911570.

The spelling of 18181943 in words is "eighteen million, one hundred eighty-one thousand, nine hundred forty-three".