218385540 has 36 divisors (see below), whose sum is σ = 662436684. Its totient is φ = 58236096.

The previous prime is 218385539. The next prime is 218385569. The reversal of 218385540 is 45583812.

It is a happy number.

218385540 is a `hidden beast` number, since 21 + 83 + 8 + 554 + 0 = 666.

218385540 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 143424576 + 74960964 = 11976^2 + 8658^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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 = 218385495 and 218385504.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 606447 + ... + 606806.

It is an arithmetic number, because the mean of its divisors is an integer number (18401019).

Almost surely, 2^218385540 is an apocalyptic number.

218385540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

218385540 is an abundant number, since it is smaller than the sum of its proper divisors (444051144).

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

218385540 is a wasteful number, since it uses less digits than its factorization.

218385540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1213268 (or 1213263 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 36.

The square root of 218385540 is about 14777.8733246702. The cubic root of 218385540 is about 602.2007512869.

The spelling of 218385540 in words is "two hundred eighteen million, three hundred eighty-five thousand, five hundred forty".