217120225 has 27 divisors (see below), whose sum is σ = 313930521. Its totient is φ = 148528800.

The previous prime is 217120223. The next prime is 217120259. The reversal of 217120225 is 522021712.

The square root of 217120225 is 14735.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 124344801 + 92775424 = 11151^2 + 9632^2 .

It is not a de Polignac number, because 217120225 - 2¹ = 217120223 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 217120196 and 217120205.

It is not an unprimeable number, because it can be changed into a prime (217120223) 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 26 ways as a sum of consecutive naturals, for example, 515515 + ... + 515935.

Almost surely, 2^217120225 is an apocalyptic number.

217120225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

217120225 is the 14735-th square number.

217120225 is the 7368-th centered octagonal number.

It is an amenable number.

217120225 is a deficient number, since it is larger than the sum of its proper divisors (96810296).

217120225 is an frugal number, since it uses more digits than its factorization.

217120225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 866 (or 433 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 22.

The cubic root of 217120225 is about 601.0354573891.

Adding to 217120225 its reverse (522021712), we get a palindrome (739141937).

The spelling of 217120225 in words is "two hundred seventeen million, one hundred twenty thousand, two hundred twenty-five".