18789989 has 4 divisors (see below), whose sum is σ = 19189824. Its totient is φ = 18390156.

The previous prime is 18789983. The next prime is 18790001. The reversal of 18789989 is 98998781.

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: 98998781 = 7 ⋅14142683.

It is a cyclic number.

It is not a de Polignac number, because 18789989 - 2⁴ = 18789973 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 (18789983) 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, 199847 + ... + 199940.

It is an arithmetic number, because the mean of its divisors is an integer number (4797456).

Almost surely, 2^18789989 is an apocalyptic number.

It is an amenable number.

18789989 is a deficient number, since it is larger than the sum of its proper divisors (399835).

18789989 is an equidigital number, since it uses as much as digits as its factorization.

18789989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 399834.

The product of its digits is 2612736, while the sum is 59.

The square root of 18789989 is about 4334.7420915206. The cubic root of 18789989 is about 265.8533733141.

The spelling of 18789989 in words is "eighteen million, seven hundred eighty-nine thousand, nine hundred eighty-nine".