218312640 has 672 divisors, whose sum is σ = 998524800. Its totient is φ = 43352064.

The previous prime is 218312597. The next prime is 218312683. The reversal of 218312640 is 46213812.

218312640 is a `hidden beast` number, since 2 + 1 + 8 + 3 + 12 + 640 = 666.

218312640 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (218312597) and next prime (218312683).

It is a tau number, because it is divible by the number of its divisors (672).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 12841912 + ... + 12841928.

It is an arithmetic number, because the mean of its divisors is an integer number (1485900).

Almost surely, 2^218312640 is an apocalyptic number.

218312640 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 218312640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (499262400).

218312640 is an abundant number, since it is smaller than the sum of its proper divisors (780212160).

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

218312640 is a wasteful number, since it uses less digits than its factorization.

218312640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 218312640 is about 14775.4065933902. The cubic root of 218312640 is about 602.1337362875.

The spelling of 218312640 in words is "two hundred eighteen million, three hundred twelve thousand, six hundred forty".