218404201685 has 4 divisors (see below), whose sum is σ = 262085042028. Its totient is φ = 174723361344.

The previous prime is 218404201681. The next prime is 218404201721. The reversal of 218404201685 is 586102404812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 35167125841 + 183237075844 = 187529^2 + 428062^2 .

It is a cyclic number.

It is not a de Polignac number, because 218404201685 - 2² = 218404201681 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 (218404201681) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21840420164 + ... + 21840420173.

It is an arithmetic number, because the mean of its divisors is an integer number (65521260507).

Almost surely, 2^218404201685 is an apocalyptic number.

It is an amenable number.

218404201685 is a deficient number, since it is larger than the sum of its proper divisors (43680840343).

218404201685 is an equidigital number, since it uses as much as digits as its factorization.

218404201685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43680840342.

The product of its (nonzero) digits is 122880, while the sum is 41.

The spelling of 218404201685 in words is "two hundred eighteen billion, four hundred four million, two hundred one thousand, six hundred eighty-five".