18993671 has 4 divisors (see below), whose sum is σ = 19041912. Its totient is φ = 18945432.

The previous prime is 18993647. The next prime is 18993679. The reversal of 18993671 is 17639981.

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-18993671 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 (18993679) 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, 23525 + ... + 24318.

It is an arithmetic number, because the mean of its divisors is an integer number (4760478).

Almost surely, 2^18993671 is an apocalyptic number.

18993671 is a deficient number, since it is larger than the sum of its proper divisors (48241).

18993671 is an equidigital number, since it uses as much as digits as its factorization.

18993671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48240.

The product of its digits is 81648, while the sum is 44.

The square root of 18993671 is about 4358.1728969833. The cubic root of 18993671 is about 266.8105329607.

The spelling of 18993671 in words is "eighteen million, nine hundred ninety-three thousand, six hundred seventy-one".