18681839 has 4 divisors (see below), whose sum is σ = 20380200. Its totient is φ = 16983480.

The previous prime is 18681833. The next prime is 18681851. The reversal of 18681839 is 93818681.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18681839 is a prime.

It is a super-2 number, since 2×18681839² = 698022216843842, which contains 22 as substring.

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 18681839.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18681833) 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, 849164 + ... + 849185.

It is an arithmetic number, because the mean of its divisors is an integer number (5095050).

Almost surely, 2^18681839 is an apocalyptic number.

18681839 is a deficient number, since it is larger than the sum of its proper divisors (1698361).

18681839 is a wasteful number, since it uses less digits than its factorization.

18681839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1698360.

The product of its digits is 82944, while the sum is 44.

The square root of 18681839 is about 4322.2492986870. The cubic root of 18681839 is about 265.3423319942.

The spelling of 18681839 in words is "eighteen million, six hundred eighty-one thousand, eight hundred thirty-nine".