18988397 has 4 divisors (see below), whose sum is σ = 18997920. Its totient is φ = 18978876.

The previous prime is 18988393. The next prime is 18988421. The reversal of 18988397 is 79388981.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 18988397 - 2² = 18988393 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 (18988393) 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, 497 + ... + 6182.

It is an arithmetic number, because the mean of its divisors is an integer number (4749480).

Almost surely, 2^18988397 is an apocalyptic number.

It is an amenable number.

18988397 is a deficient number, since it is larger than the sum of its proper divisors (9523).

18988397 is an equidigital number, since it uses as much as digits as its factorization.

18988397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9522.

The product of its digits is 870912, while the sum is 53.

The square root of 18988397 is about 4357.5677849002. The cubic root of 18988397 is about 266.7858354528.

The spelling of 18988397 in words is "eighteen million, nine hundred eighty-eight thousand, three hundred ninety-seven".