666917539 has 4 divisors (see below), whose sum is σ = 688431040. Its totient is φ = 645404040.

The previous prime is 666917527. The next prime is 666917579. The reversal of 666917539 is 935719666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 666917539 - 2²⁹ = 130046627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666917509) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10756704 + ... + 10756765.

It is an arithmetic number, because the mean of its divisors is an integer number (172107760).

Almost surely, 2^666917539 is an apocalyptic number.

666917539 is a deficient number, since it is larger than the sum of its proper divisors (21513501).

666917539 is a wasteful number, since it uses less digits than its factorization.

666917539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21513500.

The product of its digits is 1837080, while the sum is 52.

The square root of 666917539 is about 25824.7466396091. The cubic root of 666917539 is about 873.6900295788.

The spelling of 666917539 in words is "six hundred sixty-six million, nine hundred seventeen thousand, five hundred thirty-nine".