217608721813 has 16 divisors (see below), whose sum is σ = 252558233856. Its totient is φ = 183646713600.

The previous prime is 217608721801. The next prime is 217608721817. The reversal of 217608721813 is 318127806712.

It is not a de Polignac number, because 217608721813 - 2²¹ = 217606624661 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 (217608721817) 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, 791506 + ... + 1030387.

It is an arithmetic number, because the mean of its divisors is an integer number (15784889616).

Almost surely, 2^217608721813 is an apocalyptic number.

It is an amenable number.

217608721813 is a deficient number, since it is larger than the sum of its proper divisors (34949512043).

217608721813 is a wasteful number, since it uses less digits than its factorization.

217608721813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1822164.

The product of its (nonzero) digits is 225792, while the sum is 46.

The spelling of 217608721813 in words is "two hundred seventeen billion, six hundred eight million, seven hundred twenty-one thousand, eight hundred thirteen".