217162728 has 128 divisors (see below), whose sum is σ = 625996800. Its totient is φ = 69709248.

The previous prime is 217162721. The next prime is 217162733. The reversal of 217162728 is 827261712.

217162728 is a `hidden beast` number, since 2 + 1 + 7 + 1 + 627 + 28 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 217162692 and 217162701.

It is not an unprimeable number, because it can be changed into a prime (217162721) 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, 956551 + ... + 956777.

It is an arithmetic number, because the mean of its divisors is an integer number (4890600).

Almost surely, 2^217162728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217162728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (312998400).

217162728 is an abundant number, since it is smaller than the sum of its proper divisors (408834072).

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

217162728 is a wasteful number, since it uses less digits than its factorization.

217162728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388 (or 378 counting only the distinct ones).

The product of its digits is 18816, while the sum is 36.

The square root of 217162728 is about 14736.4421757763. The cubic root of 217162728 is about 601.0746739772.

The spelling of 217162728 in words is "two hundred seventeen million, one hundred sixty-two thousand, seven hundred twenty-eight".