18681943 has 4 divisors (see below), whose sum is σ = 21350800. Its totient is φ = 16013088.

The previous prime is 18681907. The next prime is 18681961. The reversal of 18681943 is 34918681.

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

It is not a de Polignac number, because 18681943 - 2⁹ = 18681431 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18681896 and 18681905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18681343) 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, 1334418 + ... + 1334431.

It is an arithmetic number, because the mean of its divisors is an integer number (5337700).

Almost surely, 2^18681943 is an apocalyptic number.

18681943 is a deficient number, since it is larger than the sum of its proper divisors (2668857).

18681943 is an equidigital number, since it uses as much as digits as its factorization.

18681943 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2668856.

The product of its digits is 41472, while the sum is 40.

The square root of 18681943 is about 4322.2613294432. The cubic root of 18681943 is about 265.3428243717.

The spelling of 18681943 in words is "eighteen million, six hundred eighty-one thousand, nine hundred forty-three".