217850931693 has 12 divisors (see below), whose sum is σ = 314697992700. Its totient is φ = 145222681536.

The previous prime is 217850931673. The next prime is 217850931731. The reversal of 217850931693 is 396139058712.

217850931693 is a `hidden beast` number, since 2 + 1 + 78 + 509 + 3 + 1 + 69 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 63623504169 + 154227427524 = 252237^2 + 392718^2 .

It is not a de Polignac number, because 217850931693 - 2¹² = 217850927597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217850931673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 816168 + ... + 1049681.

It is an arithmetic number, because the mean of its divisors is an integer number (26224832725).

Almost surely, 2^217850931693 is an apocalyptic number.

It is an amenable number.

217850931693 is a deficient number, since it is larger than the sum of its proper divisors (96847061007).

217850931693 is a wasteful number, since it uses less digits than its factorization.

217850931693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1878828 (or 1878825 counting only the distinct ones).

The product of its (nonzero) digits is 2449440, while the sum is 54.

The spelling of 217850931693 in words is "two hundred seventeen billion, eight hundred fifty million, nine hundred thirty-one thousand, six hundred ninety-three".