666661205 has 32 divisors (see below), whose sum is σ = 971066880. Its totient is φ = 428912640.

The previous prime is 666661201. The next prime is 666661277. The reversal of 666661205 is 502166666.

It is not a de Polignac number, because 666661205 - 2² = 666661201 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666661201) by changing a digit.

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, 212045 + ... + 215165.

It is an arithmetic number, because the mean of its divisors is an integer number (30345840).

Almost surely, 2^666661205 is an apocalyptic number.

It is an amenable number.

666661205 is a deficient number, since it is larger than the sum of its proper divisors (304405675).

666661205 is a wasteful number, since it uses less digits than its factorization.

666661205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3509.

The product of its (nonzero) digits is 77760, while the sum is 38.

The square root of 666661205 is about 25819.7832097793. The cubic root of 666661205 is about 873.5780791271.

The spelling of 666661205 in words is "six hundred sixty-six million, six hundred sixty-one thousand, two hundred five".