666661365 has 24 divisors (see below), whose sum is σ = 1160610360. Its totient is φ = 353994624.

The previous prime is 666661363. The next prime is 666661381. The reversal of 666661365 is 563166666.

It can be written as a sum of positive squares in 4 ways, for example, as 189282564 + 477378801 = 13758^2 + 21849^2 .

It is not a de Polignac number, because 666661365 - 2¹ = 666661363 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 666661365.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666661363) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22042 + ... + 42651.

It is an arithmetic number, because the mean of its divisors is an integer number (48358765).

Almost surely, 2^666661365 is an apocalyptic number.

It is an amenable number.

666661365 is a deficient number, since it is larger than the sum of its proper divisors (493948995).

666661365 is a wasteful number, since it uses less digits than its factorization.

666661365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64933 (or 64930 counting only the distinct ones).

The product of its digits is 699840, while the sum is 45.

The square root of 666661365 is about 25819.7863081785. The cubic root of 666661365 is about 873.5781490139.

The spelling of 666661365 in words is "six hundred sixty-six million, six hundred sixty-one thousand, three hundred sixty-five".