218618640 has 240 divisors, whose sum is σ = 794400048. Its totient is φ = 53673984.

The previous prime is 218618629. The next prime is 218618651. The reversal of 218618640 is 46816812.

218618640 is a `hidden beast` number, since 2 + 1 + 8 + 6 + 1 + 8 + 640 = 666.

It is an interprime number because it is at equal distance from previous prime (218618629) and next prime (218618651).

It can be written as a sum of positive squares in 8 ways, for example, as 1115136 + 217503504 = 1056^2 + 14748^2 .

It is a tau number, because it is divible by the number of its divisors (240).

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

It is a junction number, because it is equal to n+sod(n) for n = 218618595 and 218618604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 648552 + ... + 648888.

Almost surely, 2^218618640 is an apocalyptic number.

218618640 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 218618640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (397200024).

218618640 is an abundant number, since it is smaller than the sum of its proper divisors (575781408).

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

218618640 is a wasteful number, since it uses less digits than its factorization.

218618640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 426 (or 417 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 218618640 is about 14785.7580123577. The cubic root of 218618640 is about 602.4149337843.

The spelling of 218618640 in words is "two hundred eighteen million, six hundred eighteen thousand, six hundred forty".