217128798 has 24 divisors (see below), whose sum is σ = 471049488. Its totient is φ = 72283392.

The previous prime is 217128797. The next prime is 217128799. The reversal of 217128798 is 897821712.

It is an interprime number because it is at equal distance from previous prime (217128797) and next prime (217128799).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217128797) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7486 + ... + 22142.

It is an arithmetic number, because the mean of its divisors is an integer number (19627062).

Almost surely, 2^217128798 is an apocalyptic number.

217128798 is an abundant number, since it is smaller than the sum of its proper divisors (253920690).

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

217128798 is a wasteful number, since it uses less digits than its factorization.

217128798 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15488 (or 15485 counting only the distinct ones).

The product of its digits is 112896, while the sum is 45.

The square root of 217128798 is about 14735.2909031346. The cubic root of 217128798 is about 601.0433679206.

The spelling of 217128798 in words is "two hundred seventeen million, one hundred twenty-eight thousand, seven hundred ninety-eight".