18424993 has 4 divisors (see below), whose sum is σ = 18559620. Its totient is φ = 18290368.

The previous prime is 18424969. The next prime is 18424999. The reversal of 18424993 is 39942481.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 39942481 = 2917 ⋅13693.

It can be written as a sum of positive squares in 2 ways, for example, as 12510369 + 5914624 = 3537^2 + 2432^2 .

It is a cyclic number.

It is not a de Polignac number, because 18424993 - 2⁵ = 18424961 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 (18424999) 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, 67108 + ... + 67381.

It is an arithmetic number, because the mean of its divisors is an integer number (4639905).

Almost surely, 2^18424993 is an apocalyptic number.

It is an amenable number.

18424993 is a deficient number, since it is larger than the sum of its proper divisors (134627).

18424993 is a wasteful number, since it uses less digits than its factorization.

18424993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134626.

The product of its digits is 62208, while the sum is 40.

The square root of 18424993 is about 4292.4343908789. The cubic root of 18424993 is about 264.1207025726.

The spelling of 18424993 in words is "eighteen million, four hundred twenty-four thousand, nine hundred ninety-three".