218981664 has 96 divisors (see below), whose sum is σ = 696790080. Its totient is φ = 66355200.

The previous prime is 218981663. The next prime is 218981681. The reversal of 218981664 is 466189812.

It is a tau number, because it is divible by the number of its divisors (96).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (218981663) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 2017 + ... + 21024.

It is an arithmetic number, because the mean of its divisors is an integer number (7258230).

Almost surely, 2^218981664 is an apocalyptic number.

218981664 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 218981664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (348395040).

218981664 is an abundant number, since it is smaller than the sum of its proper divisors (477808416).

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

218981664 is a wasteful number, since it uses less digits than its factorization.

218981664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23071 (or 23057 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 218981664 is about 14798.0290579523. The cubic root of 218981664 is about 602.7481931720.

The spelling of 218981664 in words is "two hundred eighteen million, nine hundred eighty-one thousand, six hundred sixty-four".