217605728 has 12 divisors (see below), whose sum is σ = 428411340. Its totient is φ = 108802848.

The previous prime is 217605721. The next prime is 217605733. The reversal of 217605728 is 827506712.

It is a zygodrome in base 2.

It is a junction number, because it is equal to n+sod(n) for n = 217605691 and 217605700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217605721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3400058 + ... + 3400121.

It is an arithmetic number, because the mean of its divisors is an integer number (35700945).

Almost surely, 2^217605728 is an apocalyptic number.

It is an amenable number.

217605728 is a deficient number, since it is larger than the sum of its proper divisors (210805612).

217605728 is an equidigital number, since it uses as much as digits as its factorization.

217605728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6800189 (or 6800181 counting only the distinct ones).

The product of its (nonzero) digits is 47040, while the sum is 38.

The square root of 217605728 is about 14751.4652831507. The cubic root of 217605728 is about 601.4831161089.

The spelling of 217605728 in words is "two hundred seventeen million, six hundred five thousand, seven hundred twenty-eight".