666586521 has 24 divisors (see below), whose sum is σ = 995354880. Its totient is φ = 429429600.

The previous prime is 666586511. The next prime is 666586523. The reversal of 666586521 is 125685666.

It is a happy number.

It is not a de Polignac number, because 666586521 - 2⁶ = 666586457 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666586523) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 261270 + ... + 263808.

It is an arithmetic number, because the mean of its divisors is an integer number (41473120).

Almost surely, 2^666586521 is an apocalyptic number.

It is an amenable number.

666586521 is a deficient number, since it is larger than the sum of its proper divisors (328768359).

666586521 is a wasteful number, since it uses less digits than its factorization.

666586521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3517 (or 3514 counting only the distinct ones).

The product of its digits is 518400, while the sum is 45.

The square root of 666586521 is about 25818.3369139068. The cubic root of 666586521 is about 873.5454564890.

The spelling of 666586521 in words is "six hundred sixty-six million, five hundred eighty-six thousand, five hundred twenty-one".