218531664 has 120 divisors (see below), whose sum is σ = 665394912. Its totient is φ = 66551040.

The previous prime is 218531659. The next prime is 218531743. The reversal of 218531664 is 466135812.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 199759 + ... + 200849.

Almost surely, 2^218531664 is an apocalyptic number.

218531664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 218531664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (332697456).

218531664 is an abundant number, since it is smaller than the sum of its proper divisors (446863248).

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

218531664 is a wasteful number, since it uses less digits than its factorization.

218531664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1225 (or 1216 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 218531664 is about 14782.8165110712. The cubic root of 218531664 is about 602.3350342368.

The spelling of 218531664 in words is "two hundred eighteen million, five hundred thirty-one thousand, six hundred sixty-four".