18943889 has 4 divisors (see below), whose sum is σ = 19455924. Its totient is φ = 18431856.

The previous prime is 18943879. The next prime is 18943901. The reversal of 18943889 is 98834981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 98834981 = 7 ⋅14119283.

It can be written as a sum of positive squares in 2 ways, for example, as 13630864 + 5313025 = 3692^2 + 2305^2 .

It is a cyclic number.

It is not a de Polignac number, because 18943889 - 2⁸ = 18943633 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18943819) 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, 255962 + ... + 256035.

It is an arithmetic number, because the mean of its divisors is an integer number (4863981).

Almost surely, 2^18943889 is an apocalyptic number.

It is an amenable number.

18943889 is a deficient number, since it is larger than the sum of its proper divisors (512035).

18943889 is an equidigital number, since it uses as much as digits as its factorization.

18943889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512034.

The product of its digits is 497664, while the sum is 50.

The square root of 18943889 is about 4352.4578113981. The cubic root of 18943889 is about 266.5772274710.

The spelling of 18943889 in words is "eighteen million, nine hundred forty-three thousand, eight hundred eighty-nine".