218121216 has 176 divisors, whose sum is σ = 634733760. Its totient is φ = 66355200.

The previous prime is 218121193. The next prime is 218121217. The reversal of 218121216 is 612121812.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (218121217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2159566 + ... + 2159666.

Almost surely, 2^218121216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 218121216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (317366880).

218121216 is an abundant number, since it is smaller than the sum of its proper divisors (416612544).

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

218121216 is a wasteful number, since it uses less digits than its factorization.

218121216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180 (or 162 counting only the distinct ones).

The product of its digits is 384, while the sum is 24.

The square root of 218121216 is about 14768.9273814993. The cubic root of 218121216 is about 601.9576943299.

The spelling of 218121216 in words is "two hundred eighteen million, one hundred twenty-one thousand, two hundred sixteen".