217685435649 has 16 divisors (see below), whose sum is σ = 316658172864. Its totient is φ = 131920228800.

The previous prime is 217685435641. The next prime is 217685435677. The reversal of 217685435649 is 946534586712.

It is a happy number.

It is not a de Polignac number, because 217685435649 - 2³ = 217685435641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 217685435592 and 217685435601.

It is not an unprimeable number, because it can be changed into a prime (217685435641) 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, 180159 + ... + 683979.

It is an arithmetic number, because the mean of its divisors is an integer number (19791135804).

Almost surely, 2^217685435649 is an apocalyptic number.

It is an amenable number.

217685435649 is a deficient number, since it is larger than the sum of its proper divisors (98972737215).

217685435649 is a wasteful number, since it uses less digits than its factorization.

217685435649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516928.

The product of its digits is 43545600, while the sum is 60.

The spelling of 217685435649 in words is "two hundred seventeen billion, six hundred eighty-five million, four hundred thirty-five thousand, six hundred forty-nine".