218205640 has 16 divisors (see below), whose sum is σ = 490962780. Its totient is φ = 87282240.

The previous prime is 218205629. The next prime is 218205641. The reversal of 218205640 is 46502812.

It can be written as a sum of positive squares in 2 ways, for example, as 199317924 + 18887716 = 14118^2 + 4346^2 .

It is a super-2 number, since 2×218205640² = 95227402655619200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 218205599 and 218205608.

It is not an unprimeable number, because it can be changed into a prime (218205641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2727531 + ... + 2727610.

Almost surely, 2^218205640 is an apocalyptic number.

218205640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

218205640 is an abundant number, since it is smaller than the sum of its proper divisors (272757140).

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

218205640 is a wasteful number, since it uses less digits than its factorization.

218205640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5455152 (or 5455148 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 218205640 is about 14771.7852678679. The cubic root of 218205640 is about 602.0353470561.

The spelling of 218205640 in words is "two hundred eighteen million, two hundred five thousand, six hundred forty".