218138778 has 192 divisors, whose sum is σ = 597663360. Its totient is φ = 58406400.

The previous prime is 218138771. The next prime is 218138779. The reversal of 218138778 is 877831812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218138771) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4115800 + ... + 4115852.

It is an arithmetic number, because the mean of its divisors is an integer number (3112830).

Almost surely, 2^218138778 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 218138778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (298831680).

218138778 is an abundant number, since it is smaller than the sum of its proper divisors (379524582).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

218138778 is a wasteful number, since it uses less digits than its factorization.

218138778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142 (or 123 counting only the distinct ones).

The product of its digits is 150528, while the sum is 45.

The square root of 218138778 is about 14769.5219286204. The cubic root of 218138778 is about 601.9738494102.

The spelling of 218138778 in words is "two hundred eighteen million, one hundred thirty-eight thousand, seven hundred seventy-eight".