217328720 has 60 divisors (see below), whose sum is σ = 587796084. Its totient is φ = 74511360.

The previous prime is 217328711. The next prime is 217328723. The reversal of 217328720 is 27823712.

It can be written as a sum of positive squares in 2 ways, for example, as 87459904 + 129868816 = 9352^2 + 11396^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217328723) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 23801 + ... + 31640.

Almost surely, 2^217328720 is an apocalyptic number.

217328720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

217328720 is an abundant number, since it is smaller than the sum of its proper divisors (370467364).

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

217328720 is a wasteful number, since it uses less digits than its factorization.

217328720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55468 (or 55455 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 32.

The square root of 217328720 is about 14742.0731242251. The cubic root of 217328720 is about 601.2277821675.

The spelling of 217328720 in words is "two hundred seventeen million, three hundred twenty-eight thousand, seven hundred twenty".