661166217 has 12 divisors (see below), whose sum is σ = 956539584. Its totient is φ = 440075160.

The previous prime is 661166201. The next prime is 661166221. The reversal of 661166217 is 712661166.

It is not a de Polignac number, because 661166217 - 2⁴ = 661166201 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661166267) 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, 52533 + ... + 63890.

It is an arithmetic number, because the mean of its divisors is an integer number (79711632).

Almost surely, 2^661166217 is an apocalyptic number.

It is an amenable number.

661166217 is a deficient number, since it is larger than the sum of its proper divisors (295373367).

661166217 is a wasteful number, since it uses less digits than its factorization.

661166217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117060 (or 117057 counting only the distinct ones).

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

The square root of 661166217 is about 25713.1526071775. The cubic root of 661166217 is about 871.1712840611.

The spelling of 661166217 in words is "six hundred sixty-one million, one hundred sixty-six thousand, two hundred seventeen".