18316993 has 4 divisors (see below), whose sum is σ = 19113408. Its totient is φ = 17520580.

The previous prime is 18316979. The next prime is 18316999. The reversal of 18316993 is 39961381.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18316993 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18316999) 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, 398173 + ... + 398218.

It is an arithmetic number, because the mean of its divisors is an integer number (4778352).

Almost surely, 2^18316993 is an apocalyptic number.

It is an amenable number.

18316993 is a deficient number, since it is larger than the sum of its proper divisors (796415).

18316993 is an equidigital number, since it uses as much as digits as its factorization.

18316993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 796414.

The product of its digits is 34992, while the sum is 40.

The square root of 18316993 is about 4279.8356276848. The cubic root of 18316993 is about 263.6036340409.

The spelling of 18316993 in words is "eighteen million, three hundred sixteen thousand, nine hundred ninety-three".