18993819 has 8 divisors (see below), whose sum is σ = 27273232. Its totient is φ = 11688480.

The previous prime is 18993809. The next prime is 18993827. The reversal of 18993819 is 91839981.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18993819 - 2⁸ = 18993563 is a prime.

It is a super-2 number, since 2×18993819² = 721530320409522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18993809) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 243472 + ... + 243549.

It is an arithmetic number, because the mean of its divisors is an integer number (3409154).

Almost surely, 2^18993819 is an apocalyptic number.

18993819 is a deficient number, since it is larger than the sum of its proper divisors (8279413).

18993819 is a wasteful number, since it uses less digits than its factorization.

18993819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 487037.

The product of its digits is 139968, while the sum is 48.

The square root of 18993819 is about 4358.1898765428. The cubic root of 18993819 is about 266.8112259609.

The spelling of 18993819 in words is "eighteen million, nine hundred ninety-three thousand, eight hundred nineteen".