218439661 has 16 divisors (see below), whose sum is σ = 242876160. Its totient is φ = 194800320.

The previous prime is 218439593. The next prime is 218439673. The reversal of 218439661 is 166934812.

It is not a de Polignac number, because 218439661 - 2¹⁷ = 218308589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218439761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 149611 + ... + 151063.

It is an arithmetic number, because the mean of its divisors is an integer number (15179760).

Almost surely, 2^218439661 is an apocalyptic number.

It is an amenable number.

218439661 is a deficient number, since it is larger than the sum of its proper divisors (24436499).

218439661 is a wasteful number, since it uses less digits than its factorization.

218439661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1716.

The product of its digits is 62208, while the sum is 40.

The square root of 218439661 is about 14779.7043610486. The cubic root of 218439661 is about 602.2504936140.

The spelling of 218439661 in words is "two hundred eighteen million, four hundred thirty-nine thousand, six hundred sixty-one".