660666851 has 4 divisors (see below), whose sum is σ = 711487392. Its totient is φ = 609846312.

The previous prime is 660666821. The next prime is 660666887. The reversal of 660666851 is 158666066.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 660666851 - 2¹⁴ = 660650467 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (660666821) 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 3 ways as a sum of consecutive naturals, for example, 25410251 + ... + 25410276.

It is an arithmetic number, because the mean of its divisors is an integer number (177871848).

Almost surely, 2^660666851 is an apocalyptic number.

660666851 is a deficient number, since it is larger than the sum of its proper divisors (50820541).

660666851 is a wasteful number, since it uses less digits than its factorization.

660666851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50820540.

The product of its (nonzero) digits is 311040, while the sum is 44.

The square root of 660666851 is about 25703.4404506478. The cubic root of 660666851 is about 870.9519025711.

The spelling of 660666851 in words is "six hundred sixty million, six hundred sixty-six thousand, eight hundred fifty-one".