18197989 has 4 divisors (see below), whose sum is σ = 18210400. Its totient is φ = 18185580.

The previous prime is 18197941. The next prime is 18198001. The reversal of 18197989 is 98979181.

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 a cyclic number.

It is not a de Polignac number, because 18197989 - 2²³ = 9809381 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 (18197929) 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, 3657 + ... + 7054.

It is an arithmetic number, because the mean of its divisors is an integer number (4552600).

Almost surely, 2^18197989 is an apocalyptic number.

It is an amenable number.

18197989 is a deficient number, since it is larger than the sum of its proper divisors (12411).

18197989 is a wasteful number, since it uses less digits than its factorization.

18197989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12410.

The product of its digits is 326592, while the sum is 52.

The square root of 18197989 is about 4265.9101021939. The cubic root of 18197989 is about 263.0315228688.

The spelling of 18197989 in words is "eighteen million, one hundred ninety-seven thousand, nine hundred eighty-nine".