217238121 has 21 divisors (see below), whose sum is σ = 333400171. Its totient is φ = 136306272.

The previous prime is 217238083. The next prime is 217238129. The reversal of 217238121 is 121832712.

The square root of 217238121 is 14739.

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

It can be written as a sum of positive squares in 3 ways, for example, as 2205225 + 215032896 = 1485^2 + 14664^2 .

It is not a de Polignac number, because 217238121 - 2²¹ = 215140969 is a prime.

It is a super-2 number, since 2×217238121² = 94384802431221282, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (217238129) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 12778705 + ... + 12778721.

Almost surely, 2^217238121 is an apocalyptic number.

217238121 is the 14739-th square number.

217238121 is the 7370-th centered octagonal number.

It is an amenable number.

217238121 is a deficient number, since it is larger than the sum of its proper divisors (116162050).

217238121 is an frugal number, since it uses more digits than its factorization.

217238121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108 (or 20 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The cubic root of 217238121 is about 601.1442248620.

The spelling of 217238121 in words is "two hundred seventeen million, two hundred thirty-eight thousand, one hundred twenty-one".