18639943 has 12 divisors (see below), whose sum is σ = 21804552. Its totient is φ = 15887760.

The previous prime is 18639911. The next prime is 18639949. The reversal of 18639943 is 34993681.

It is not a de Polignac number, because 18639943 - 2⁵ = 18639911 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18639943.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18639949) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8688 + ... + 10618.

It is an arithmetic number, because the mean of its divisors is an integer number (1817046).

Almost surely, 2^18639943 is an apocalyptic number.

18639943 is a deficient number, since it is larger than the sum of its proper divisors (3164609).

18639943 is a wasteful number, since it uses less digits than its factorization.

18639943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2142 (or 2135 counting only the distinct ones).

The product of its digits is 139968, while the sum is 43.

The square root of 18639943 is about 4317.4000277945. The cubic root of 18639943 is about 265.1438307850.

The spelling of 18639943 in words is "eighteen million, six hundred thirty-nine thousand, nine hundred forty-three".