217916393858 has 24 divisors (see below), whose sum is σ = 330345624756. Its totient is φ = 107813217600.

The previous prime is 217916393833. The next prime is 217916393867. The reversal of 217916393858 is 858393619712.

It can be written as a sum of positive squares in 6 ways, for example, as 200835733609 + 17080660249 = 448147^2 + 130693^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 217916393858.

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 11 ways as a sum of consecutive naturals, for example, 61959116 + ... + 61962632.

Almost surely, 2^217916393858 is an apocalyptic number.

217916393858 is a deficient number, since it is larger than the sum of its proper divisors (112429230898).

217916393858 is a wasteful number, since it uses less digits than its factorization.

217916393858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6758 (or 6657 counting only the distinct ones).

The product of its digits is 19595520, while the sum is 62.

The spelling of 217916393858 in words is "two hundred seventeen billion, nine hundred sixteen million, three hundred ninety-three thousand, eight hundred fifty-eight".