213818128705 has 4 divisors (see below), whose sum is σ = 256581754452. Its totient is φ = 171054502960.

The previous prime is 213818128673. The next prime is 213818128747. The reversal of 213818128705 is 507821818312.

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 125256535056 + 88561593649 = 353916^2 + 297593^2 .

It is not a de Polignac number, because 213818128705 - 2⁵ = 213818128673 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21381812866 + ... + 21381812875.

It is an arithmetic number, because the mean of its divisors is an integer number (64145438613).

Almost surely, 2^213818128705 is an apocalyptic number.

It is an amenable number.

213818128705 is a deficient number, since it is larger than the sum of its proper divisors (42763625747).

213818128705 is an equidigital number, since it uses as much as digits as its factorization.

213818128705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42763625746.

The product of its (nonzero) digits is 215040, while the sum is 46.

The spelling of 213818128705 in words is "two hundred thirteen billion, eight hundred eighteen million, one hundred twenty-eight thousand, seven hundred five".