218256640 has 72 divisors (see below), whose sum is σ = 597502080. Its totient is φ = 74827776.

The previous prime is 218256607. The next prime is 218256679. The reversal of 218256640 is 46652812.

218256640 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 218256596 and 218256605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3220 + ... + 21139.

It is an arithmetic number, because the mean of its divisors is an integer number (8298640).

Almost surely, 2^218256640 is an apocalyptic number.

218256640 is a gapful number since it is divisible by the number (20) 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 218256640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (298751040).

218256640 is an abundant number, since it is smaller than the sum of its proper divisors (379245440).

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

218256640 is an equidigital number, since it uses as much as digits as its factorization.

218256640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24387 (or 24373 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 34.

The square root of 218256640 is about 14773.5114309361. The cubic root of 218256640 is about 602.0822468688.

The spelling of 218256640 in words is "two hundred eighteen million, two hundred fifty-six thousand, six hundred forty".