217648640 has 160 divisors (see below), whose sum is σ = 583355520. Its totient is φ = 77209600.

The previous prime is 217648631. The next prime is 217648643. The reversal of 217648640 is 46846712.

217648640 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (160).

It is a junction number, because it is equal to n+sod(n) for n = 217648594 and 217648603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217648643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1661375 + ... + 1661505.

It is an arithmetic number, because the mean of its divisors is an integer number (3645972).

Almost surely, 2^217648640 is an apocalyptic number.

217648640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217648640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (291677760).

217648640 is an abundant number, since it is smaller than the sum of its proper divisors (365706880).

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

217648640 is a wasteful number, since it uses less digits than its factorization.

217648640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224 (or 208 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 38.

The square root of 217648640 is about 14752.9197110267. The cubic root of 217648640 is about 601.5226511390.

The spelling of 217648640 in words is "two hundred seventeen million, six hundred forty-eight thousand, six hundred forty".