18697989 has 4 divisors (see below), whose sum is σ = 24930656. Its totient is φ = 12465324.

The previous prime is 18697967. The next prime is 18698027. The reversal of 18697989 is 98979681.

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 an emirpimes, since its reverse is a distinct semiprime: 98979681 = 3 ⋅32993227.

It is not a de Polignac number, because 18697989 - 2⁹ = 18697477 is a prime.

It is a super-2 number, since 2×18697989² = 699229585288242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18697949) 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, 3116329 + ... + 3116334.

It is an arithmetic number, because the mean of its divisors is an integer number (6232664).

Almost surely, 2^18697989 is an apocalyptic number.

It is an amenable number.

18697989 is a deficient number, since it is larger than the sum of its proper divisors (6232667).

18697989 is an equidigital number, since it uses as much as digits as its factorization.

18697989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6232666.

The product of its digits is 1959552, while the sum is 57.

The square root of 18697989 is about 4324.1171353237. The cubic root of 18697989 is about 265.4187706577.

The spelling of 18697989 in words is "eighteen million, six hundred ninety-seven thousand, nine hundred eighty-nine".