668759521 has 16 divisors (see below), whose sum is σ = 695123968. Its totient is φ = 642978000.

The previous prime is 668759519. The next prime is 668759527. The reversal of 668759521 is 125957866.

It is a cyclic number.

It is not a de Polignac number, because 668759521 - 2¹ = 668759519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (668759527) 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, 824206 + ... + 825016.

It is an arithmetic number, because the mean of its divisors is an integer number (43445248).

Almost surely, 2^668759521 is an apocalyptic number.

It is an amenable number.

668759521 is a deficient number, since it is larger than the sum of its proper divisors (26364447).

668759521 is a wasteful number, since it uses less digits than its factorization.

668759521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1132.

The product of its digits is 907200, while the sum is 49.

The square root of 668759521 is about 25860.3851672785. The cubic root of 668759521 is about 874.4936481525.

The spelling of 668759521 in words is "six hundred sixty-eight million, seven hundred fifty-nine thousand, five hundred twenty-one".