18997438 has 4 divisors (see below), whose sum is σ = 28496160. Its totient is φ = 9498718.

The previous prime is 18997427. The next prime is 18997439. The reversal of 18997438 is 83479981.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 18997391 and 18997400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18997439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4749358 + ... + 4749361.

It is an arithmetic number, because the mean of its divisors is an integer number (7124040).

Almost surely, 2^18997438 is an apocalyptic number.

18997438 is a deficient number, since it is larger than the sum of its proper divisors (9498722).

18997438 is an equidigital number, since it uses as much as digits as its factorization.

18997438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9498721.

The product of its digits is 435456, while the sum is 49.

The square root of 18997438 is about 4358.6050520780. The cubic root of 18997438 is about 266.8281705699.

The spelling of 18997438 in words is "eighteen million, nine hundred ninety-seven thousand, four hundred thirty-eight".