665221305 has 48 divisors (see below), whose sum is σ = 1310981760. Its totient is φ = 286207488.

The previous prime is 665221303. The next prime is 665221313. The reversal of 665221305 is 503122566.

It is not a de Polignac number, because 665221305 - 2¹ = 665221303 is a prime.

It is not an unprimeable number, because it can be changed into a prime (665221303) 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 47 ways as a sum of consecutive naturals, for example, 14125 + ... + 39114.

It is an arithmetic number, because the mean of its divisors is an integer number (27312120).

Almost surely, 2^665221305 is an apocalyptic number.

It is an amenable number.

665221305 is a deficient number, since it is larger than the sum of its proper divisors (645760455).

665221305 is a wasteful number, since it uses less digits than its factorization.

665221305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53278 (or 53271 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 30.

The square root of 665221305 is about 25791.8844794249. The cubic root of 665221305 is about 872.9486880850.

The spelling of 665221305 in words is "six hundred sixty-five million, two hundred twenty-one thousand, three hundred five".