666491600 has 60 divisors (see below), whose sum is σ = 1603789836. Its totient is φ = 266173440.

The previous prime is 666491597. The next prime is 666491611. The reversal of 666491600 is 6194666.

It can be written as a sum of positive squares in 6 ways, for example, as 31854736 + 634636864 = 5644^2 + 25192^2 .

It is a super-2 number, since 2×666491600² = 888422105741120000, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 412394 + ... + 414006.

Almost surely, 2^666491600 is an apocalyptic number.

It is an amenable number.

666491600 is an abundant number, since it is smaller than the sum of its proper divisors (937298236).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666491600 is a wasteful number, since it uses less digits than its factorization.

666491600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2664 (or 2653 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 38.

The square root of 666491600 is about 25816.4986007011. The cubic root of 666491600 is about 873.5039906319.

The spelling of 666491600 in words is "six hundred sixty-six million, four hundred ninety-one thousand, six hundred".