218321408 has 30 divisors (see below), whose sum is σ = 436885449. Its totient is φ = 108993536.

The previous prime is 218321401. The next prime is 218321431. The reversal of 218321408 is 804123812.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 201412864 + 16908544 = 14192^2 + 4112^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=10448.

It is a super-2 number, since 2×218321408² = 95328474382204928, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218321401) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 334010 + ... + 334662.

Almost surely, 2^218321408 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 218321408

218321408 is an abundant number, since it is smaller than the sum of its proper divisors (218564041).

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

218321408 is an frugal number, since it uses more digits than its factorization.

218321408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1324 (or 655 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 29.

The square root of 218321408 is about 14775.7032996741. The cubic root of 218321408 is about 602.1417972621.

The spelling of 218321408 in words is "two hundred eighteen million, three hundred twenty-one thousand, four hundred eight".