217128912 has 160 divisors (see below), whose sum is σ = 753285120. Its totient is φ = 52047360.

The previous prime is 217128911. The next prime is 217128931. The reversal of 217128912 is 219821712.

217128912 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217128911) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45789 + ... + 50307.

It is an arithmetic number, because the mean of its divisors is an integer number (4708032).

Almost surely, 2^217128912 is an apocalyptic number.

217128912 is a gapful number since it is divisible by the number (22) 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 217128912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (376642560).

217128912 is an abundant number, since it is smaller than the sum of its proper divisors (536156208).

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

217128912 is a wasteful number, since it uses less digits than its factorization.

217128912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4561 (or 4555 counting only the distinct ones).

The product of its digits is 4032, while the sum is 33.

The square root of 217128912 is about 14735.2947713984. The cubic root of 217128912 is about 601.0434731100.

The spelling of 217128912 in words is "two hundred seventeen million, one hundred twenty-eight thousand, nine hundred twelve".