217318225 has 12 divisors (see below), whose sum is σ = 285326604. Its totient is φ = 163627520.

The previous prime is 217318217. The next prime is 217318229. The reversal of 217318225 is 522813712.

It can be written as a sum of positive squares in 6 ways, for example, as 4129024 + 213189201 = 2032^2 + 14601^2 .

It is not a de Polignac number, because 217318225 - 2³ = 217318217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217318229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 255244 + ... + 256093.

It is an arithmetic number, because the mean of its divisors is an integer number (23777217).

Almost surely, 2^217318225 is an apocalyptic number.

217318225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

217318225 is a deficient number, since it is larger than the sum of its proper divisors (68008379).

217318225 is a wasteful number, since it uses less digits than its factorization.

217318225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511364 (or 511359 counting only the distinct ones).

The product of its digits is 6720, while the sum is 31.

The square root of 217318225 is about 14741.7171659207. The cubic root of 217318225 is about 601.2181040677.

The spelling of 217318225 in words is "two hundred seventeen million, three hundred eighteen thousand, two hundred twenty-five".