218138789 has 4 divisors (see below), whose sum is σ = 237969600. Its totient is φ = 198307980.

The previous prime is 218138779. The next prime is 218138813. The reversal of 218138789 is 987831812.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-218138789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218138719) 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, 9915389 + ... + 9915410.

It is an arithmetic number, because the mean of its divisors is an integer number (59492400).

Almost surely, 2^218138789 is an apocalyptic number.

It is an amenable number.

218138789 is a deficient number, since it is larger than the sum of its proper divisors (19830811).

218138789 is a wasteful number, since it uses less digits than its factorization.

218138789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19830810.

The product of its digits is 193536, while the sum is 47.

The square root of 218138789 is about 14769.5223010089. The cubic root of 218138789 is about 601.9738595287.

The spelling of 218138789 in words is "two hundred eighteen million, one hundred thirty-eight thousand, seven hundred eighty-nine".