217689664 has 56 divisors (see below), whose sum is σ = 461881728. Its totient is φ = 101544960.

The previous prime is 217689649. The next prime is 217689713. The reversal of 217689664 is 466986712.

217689664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58549 + ... + 62155.

It is an arithmetic number, because the mean of its divisors is an integer number (8247888).

Almost surely, 2^217689664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217689664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (230940864).

217689664 is an abundant number, since it is smaller than the sum of its proper divisors (244192064).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217689664 is a wasteful number, since it uses less digits than its factorization.

217689664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3683 (or 3673 counting only the distinct ones).

The product of its digits is 870912, while the sum is 49.

The square root of 217689664 is about 14754.3100143653. The cubic root of 217689664 is about 601.5604418874.

The spelling of 217689664 in words is "two hundred seventeen million, six hundred eighty-nine thousand, six hundred sixty-four".