18898989 has 4 divisors (see below), whose sum is σ = 25198656. Its totient is φ = 12599324.

The previous prime is 18898987. The next prime is 18899003. The reversal of 18898989 is 98989881.

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: 98989881 = 3 ⋅32996627.

It is a cyclic number.

It is not a de Polignac number, because 18898989 - 2¹ = 18898987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18898987) 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, 3149829 + ... + 3149834.

It is an arithmetic number, because the mean of its divisors is an integer number (6299664).

Almost surely, 2^18898989 is an apocalyptic number.

It is an amenable number.

18898989 is a deficient number, since it is larger than the sum of its proper divisors (6299667).

18898989 is an equidigital number, since it uses as much as digits as its factorization.

18898989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6299666.

The product of its digits is 2985984, while the sum is 60.

The square root of 18898989 is about 4347.2967462551. The cubic root of 18898989 is about 266.3664508564.

It can be divided in two parts, 1889 and 8989, that added together give a triangular number (10878 = T₁₄₇).

The spelling of 18898989 in words is "eighteen million, eight hundred ninety-eight thousand, nine hundred eighty-nine".