218220640 has 48 divisors (see below), whose sum is σ = 562418640. Its totient is φ = 79352320.

The previous prime is 218220617. The next prime is 218220649. The reversal of 218220640 is 46022812.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218220649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60235 + ... + 63754.

It is an arithmetic number, because the mean of its divisors is an integer number (11717055).

Almost surely, 2^218220640 is an apocalyptic number.

218220640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

218220640 is an abundant number, since it is smaller than the sum of its proper divisors (344198000).

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

218220640 is a wasteful number, since it uses less digits than its factorization.

218220640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124015 (or 124007 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 218220640 is about 14772.2929838262. The cubic root of 218220640 is about 602.0491418771.

It can be divided in two parts, 2182 and 20640, that added together give a palindrome (22822).

The spelling of 218220640 in words is "two hundred eighteen million, two hundred twenty thousand, six hundred forty".