18719989 has 4 divisors (see below), whose sum is σ = 18735424. Its totient is φ = 18704556.

The previous prime is 18719983. The next prime is 18720083. The reversal of 18719989 is 98991781.

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: 98991781 = 7 ⋅14141683.

It is a cyclic number.

It is not a de Polignac number, because 18719989 - 2⁵ = 18719957 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 (18719983) 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, 5727 + ... + 8380.

It is an arithmetic number, because the mean of its divisors is an integer number (4683856).

Almost surely, 2^18719989 is an apocalyptic number.

It is an amenable number.

18719989 is a deficient number, since it is larger than the sum of its proper divisors (15435).

18719989 is a wasteful number, since it uses less digits than its factorization.

18719989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15434.

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

The square root of 18719989 is about 4326.6602593687. The cubic root of 18719989 is about 265.5228268447.

The spelling of 18719989 in words is "eighteen million, seven hundred nineteen thousand, nine hundred eighty-nine".