217252661 has 2 divisors, whose sum is σ = 217252662. Its totient is φ = 217252660.

The previous prime is 217252643. The next prime is 217252663. The reversal of 217252661 is 166252712.

217252661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 121330225 + 95922436 = 11015^2 + 9794^2 .

It is a cyclic number.

It is not a de Polignac number, because 217252661 - 2⁶ = 217252597 is a prime.

Together with 217252663, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217252663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108626330 + 108626331.

It is an arithmetic number, because the mean of its divisors is an integer number (108626331).

Almost surely, 2^217252661 is an apocalyptic number.

It is an amenable number.

217252661 is a deficient number, since it is larger than the sum of its proper divisors (1).

217252661 is an equidigital number, since it uses as much as digits as its factorization.

217252661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 32.

The square root of 217252661 is about 14739.4932409496. The cubic root of 217252661 is about 601.1576363234.

The spelling of 217252661 in words is "two hundred seventeen million, two hundred fifty-two thousand, six hundred sixty-one".