217240121 has 4 divisors (see below), whose sum is σ = 248274432. Its totient is φ = 186205812.

The previous prime is 217240117. The next prime is 217240123. The reversal of 217240121 is 121042712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 217240121 - 2² = 217240117 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 217240093 and 217240102.

It is not an unprimeable number, because it can be changed into a prime (217240123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15517145 + ... + 15517158.

It is an arithmetic number, because the mean of its divisors is an integer number (62068608).

Almost surely, 2^217240121 is an apocalyptic number.

It is an amenable number.

217240121 is a deficient number, since it is larger than the sum of its proper divisors (31034311).

217240121 is an equidigital number, since it uses as much as digits as its factorization.

217240121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31034310.

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 217240121 is about 14739.0678470519. The cubic root of 217240121 is about 601.1460696652.

Adding to 217240121 its reverse (121042712), we get a palindrome (338282833).

The spelling of 217240121 in words is "two hundred seventeen million, two hundred forty thousand, one hundred twenty-one".