666337521 has 8 divisors (see below), whose sum is σ = 891908064. Its totient is φ = 442496000.

The previous prime is 666337493. The next prime is 666337547. The reversal of 666337521 is 125733666.

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

It is a cyclic number.

It is not a de Polignac number, because 666337521 - 2¹³ = 666329329 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 666337521.

It is not an unprimeable number, because it can be changed into a prime (666337561) 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, 431355 + ... + 432896.

It is an arithmetic number, because the mean of its divisors is an integer number (111488508).

Almost surely, 2^666337521 is an apocalyptic number.

It is an amenable number.

666337521 is a deficient number, since it is larger than the sum of its proper divisors (225570543).

666337521 is a wasteful number, since it uses less digits than its factorization.

666337521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864511.

The product of its digits is 136080, while the sum is 39.

The square root of 666337521 is about 25813.5143093690. The cubic root of 666337521 is about 873.4366734573.

The spelling of 666337521 in words is "six hundred sixty-six million, three hundred thirty-seven thousand, five hundred twenty-one".