666505509 has 8 divisors (see below), whose sum is σ = 893811552. Its totient is φ = 441768240.

The previous prime is 666505507. The next prime is 666505513. The reversal of 666505509 is 905505666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 666505509 - 2¹ = 666505507 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666505501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 641587 + ... + 642624.

It is an arithmetic number, because the mean of its divisors is an integer number (111726444).

Almost surely, 2^666505509 is an apocalyptic number.

It is an amenable number.

666505509 is a deficient number, since it is larger than the sum of its proper divisors (227306043).

666505509 is a wasteful number, since it uses less digits than its factorization.

666505509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1284387.

The product of its (nonzero) digits is 243000, while the sum is 42.

The square root of 666505509 is about 25816.7679812946. The cubic root of 666505509 is about 873.5100669688.

The spelling of 666505509 in words is "six hundred sixty-six million, five hundred five thousand, five hundred nine".