665704215 has 24 divisors (see below), whose sum is σ = 1258787088. Its totient is φ = 322765440.

The previous prime is 665704213. The next prime is 665704217. The reversal of 665704215 is 512407566.

It is a happy number.

665704215 is a `hidden beast` number, since 66 + 570 + 4 + 21 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (665704213) and next prime (665704217).

It is not a de Polignac number, because 665704215 - 2¹ = 665704213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 665704215.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665704213) 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, 671934 + ... + 672923.

It is an arithmetic number, because the mean of its divisors is an integer number (52449462).

Almost surely, 2^665704215 is an apocalyptic number.

665704215 is a deficient number, since it is larger than the sum of its proper divisors (593082873).

665704215 is a wasteful number, since it uses less digits than its factorization.

665704215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1344879 (or 1344876 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 36.

The square root of 665704215 is about 25801.2444467316. The cubic root of 665704215 is about 873.1598727845.

The spelling of 665704215 in words is "six hundred sixty-five million, seven hundred four thousand, two hundred fifteen".