217055728 has 40 divisors (see below), whose sum is σ = 448565040. Its totient is φ = 101391360.

The previous prime is 217055717. The next prime is 217055731. The reversal of 217055728 is 827550712.

It is a super-2 number, since 2×217055728² = 94226378115219968, which contains 22 as substring.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 34938 + ... + 40678.

It is an arithmetic number, because the mean of its divisors is an integer number (11214126).

Almost surely, 2^217055728 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 217055728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (224282520).

217055728 is an abundant number, since it is smaller than the sum of its proper divisors (231509312).

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

217055728 is a wasteful number, since it uses less digits than its factorization.

217055728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5905 (or 5899 counting only the distinct ones).

The product of its (nonzero) digits is 39200, while the sum is 37.

The square root of 217055728 is about 14732.8112728019. The cubic root of 217055728 is about 600.9759376414.

The spelling of 217055728 in words is "two hundred seventeen million, fifty-five thousand, seven hundred twenty-eight".