217189121 has 4 divisors (see below), whose sum is σ = 217221972. Its totient is φ = 217156272.

The previous prime is 217189081. The next prime is 217189123. The reversal of 217189121 is 121981712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 36663025 + 180526096 = 6055^2 + 13436^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217189121 is a prime.

It is a super-2 number, since 2×217189121² = 94342228561505282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217189123) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 2666 + ... + 21011.

It is an arithmetic number, because the mean of its divisors is an integer number (54305493).

Almost surely, 2^217189121 is an apocalyptic number.

It is an amenable number.

217189121 is a deficient number, since it is larger than the sum of its proper divisors (32851).

217189121 is an equidigital number, since it uses as much as digits as its factorization.

217189121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32850.

The product of its digits is 2016, while the sum is 32.

The square root of 217189121 is about 14737.3376496571. The cubic root of 217189121 is about 601.0990236455.

The spelling of 217189121 in words is "two hundred seventeen million, one hundred eighty-nine thousand, one hundred twenty-one".