646217712647 has 32 divisors (see below), whose sum is σ = 729466214400. Its totient is φ = 567998209152.

The previous prime is 646217712641. The next prime is 646217712649. The reversal of 646217712647 is 746217712646.

It is a cyclic number.

It is not a de Polignac number, because 646217712647 - 2¹² = 646217708551 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 (646217712641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 181571054 + ... + 181574612.

It is an arithmetic number, because the mean of its divisors is an integer number (22795819200).

Almost surely, 2^646217712647 is an apocalyptic number.

646217712647 is a deficient number, since it is larger than the sum of its proper divisors (83248501753).

646217712647 is a wasteful number, since it uses less digits than its factorization.

646217712647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6167.

The product of its digits is 4741632, while the sum is 53.

Subtracting 646217712647 from its reverse (746217712646), we obtain a palindrome (99999999999).

The spelling of 646217712647 in words is "six hundred forty-six billion, two hundred seventeen million, seven hundred twelve thousand, six hundred forty-seven".