217229661 has 16 divisors (see below), whose sum is σ = 351078720. Its totient is φ = 131654160.

The previous prime is 217229653. The next prime is 217229671. The reversal of 217229661 is 166922712.

It is not a de Polignac number, because 217229661 - 2³ = 217229653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217229651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 365410 + ... + 366003.

It is an arithmetic number, because the mean of its divisors is an integer number (21942420).

Almost surely, 2^217229661 is an apocalyptic number.

It is an amenable number.

217229661 is a deficient number, since it is larger than the sum of its proper divisors (133849059).

217229661 is a wasteful number, since it uses less digits than its factorization.

217229661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 731433 (or 731427 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 217229661 is about 14738.7130035156. The cubic root of 217229661 is about 601.1364212191.

The spelling of 217229661 in words is "two hundred seventeen million, two hundred twenty-nine thousand, six hundred sixty-one".