217125261 has 12 divisors (see below), whose sum is σ = 317405088. Its totient is φ = 143005704.

The previous prime is 217125257. The next prime is 217125269. The reversal of 217125261 is 162521712.

It is not a de Polignac number, because 217125261 - 2² = 217125257 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217125269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 144585 + ... + 146078.

It is an arithmetic number, because the mean of its divisors is an integer number (26450424).

Almost surely, 2^217125261 is an apocalyptic number.

It is an amenable number.

217125261 is a deficient number, since it is larger than the sum of its proper divisors (100279827).

217125261 is a wasteful number, since it uses less digits than its factorization.

217125261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290752 (or 290749 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 217125261 is about 14735.1708846555. The cubic root of 217125261 is about 601.0401042633.

Adding to 217125261 its reverse (162521712), we get a palindrome (379646973).

The spelling of 217125261 in words is "two hundred seventeen million, one hundred twenty-five thousand, two hundred sixty-one".