18889997 has 4 divisors (see below), whose sum is σ = 21588576. Its totient is φ = 16191420.

The previous prime is 18889993. The next prime is 18889999. The reversal of 18889997 is 79998881.

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 not a de Polignac number, because 18889997 - 2² = 18889993 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 (18889993) 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, 1349279 + ... + 1349292.

It is an arithmetic number, because the mean of its divisors is an integer number (5397144).

Almost surely, 2^18889997 is an apocalyptic number.

It is an amenable number.

18889997 is a deficient number, since it is larger than the sum of its proper divisors (2698579).

18889997 is an equidigital number, since it uses as much as digits as its factorization.

18889997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2698578.

The product of its digits is 2612736, while the sum is 59.

The square root of 18889997 is about 4346.2624172960. The cubic root of 18889997 is about 266.3241990884.

Subtracting from 18889997 its product of digits (2612736), we obtain a palindrome (16277261).

The spelling of 18889997 in words is "eighteen million, eight hundred eighty-nine thousand, nine hundred ninety-seven".