18697993 has 4 divisors (see below), whose sum is σ = 18708228. Its totient is φ = 18687760.

The previous prime is 18697967. The next prime is 18698027. The reversal of 18697993 is 39979681.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 139129 + 18558864 = 373^2 + 4308^2 .

It is a cyclic number.

It is not a de Polignac number, because 18697993 - 2⁵ = 18697961 is a prime.

It is a super-2 number, since 2×18697993² = 699229884456098, 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 18697993.

It is not an unprimeable number, because it can be changed into a prime (18697193) 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, 1546 + ... + 6307.

It is an arithmetic number, because the mean of its divisors is an integer number (4677057).

Almost surely, 2^18697993 is an apocalyptic number.

It is an amenable number.

18697993 is a deficient number, since it is larger than the sum of its proper divisors (10235).

18697993 is an equidigital number, since it uses as much as digits as its factorization.

18697993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10234.

The product of its digits is 734832, while the sum is 52.

The square root of 18697993 is about 4324.1175978458. The cubic root of 18697993 is about 265.4187895844.

The spelling of 18697993 in words is "eighteen million, six hundred ninety-seven thousand, nine hundred ninety-three".