666316557 has 16 divisors (see below), whose sum is σ = 1021176000. Its totient is φ = 428892912.

The previous prime is 666316537. The next prime is 666316589. The reversal of 666316557 is 755613666.

It is not a de Polignac number, because 666316557 - 2⁷ = 666316429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666316507) 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, 424707 + ... + 426272.

It is an arithmetic number, because the mean of its divisors is an integer number (63823500).

Almost surely, 2^666316557 is an apocalyptic number.

It is an amenable number.

666316557 is a deficient number, since it is larger than the sum of its proper divisors (354859443).

666316557 is a wasteful number, since it uses less digits than its factorization.

666316557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851017 (or 851011 counting only the distinct ones).

The product of its digits is 680400, while the sum is 45.

The square root of 666316557 is about 25813.1082398072. The cubic root of 666316557 is about 873.4275134757.

It can be divided in two parts, 6663 and 16557, that added together give a triangular number (23220 = T₂₁₅).

The spelling of 666316557 in words is "six hundred sixty-six million, three hundred sixteen thousand, five hundred fifty-seven".