668406606 has 64 divisors (see below), whose sum is σ = 1560688128. Its totient is φ = 186899328.

The previous prime is 668406581. The next prime is 668406617. The reversal of 668406606 is 606604866.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

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 31 ways as a sum of consecutive naturals, for example, 486136 + ... + 487508.

It is an arithmetic number, because the mean of its divisors is an integer number (24385752).

Almost surely, 2^668406606 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 668406606, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (780344064).

668406606 is an abundant number, since it is smaller than the sum of its proper divisors (892281522).

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

668406606 is a wasteful number, since it uses less digits than its factorization.

668406606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1625.

The product of its (nonzero) digits is 248832, while the sum is 42.

The square root of 668406606 is about 25853.5607992400. The cubic root of 668406606 is about 874.3397930321.

The spelling of 668406606 in words is "six hundred sixty-eight million, four hundred six thousand, six hundred six".