666617217 has 24 divisors (see below), whose sum is σ = 1036303776. Its totient is φ = 380052288.

The previous prime is 666617213. The next prime is 666617219. The reversal of 666617217 is 712716666.

It is not a de Polignac number, because 666617217 - 2² = 666617213 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666617213) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 62218 + ... + 72140.

It is an arithmetic number, because the mean of its divisors is an integer number (43179324).

Almost surely, 2^666617217 is an apocalyptic number.

It is an amenable number.

666617217 is a deficient number, since it is larger than the sum of its proper divisors (369686559).

666617217 is a wasteful number, since it uses less digits than its factorization.

666617217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10397 (or 10390 counting only the distinct ones).

The product of its digits is 127008, while the sum is 42.

The square root of 666617217 is about 25818.9313682809. The cubic root of 666617217 is about 873.5588650708.

The spelling of 666617217 in words is "six hundred sixty-six million, six hundred seventeen thousand, two hundred seventeen".