665647407 has 24 divisors (see below), whose sum is σ = 993802368. Its totient is φ = 428889600.

The previous prime is 665647399. The next prime is 665647453. The reversal of 665647407 is 704746566.

It is a happy number.

It is not a de Polignac number, because 665647407 - 2³ = 665647399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665647487) 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, 378843 + ... + 380595.

It is an arithmetic number, because the mean of its divisors is an integer number (41408432).

Almost surely, 2^665647407 is an apocalyptic number.

665647407 is a deficient number, since it is larger than the sum of its proper divisors (328154961).

665647407 is a wasteful number, since it uses less digits than its factorization.

665647407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3151 (or 3148 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 45.

The square root of 665647407 is about 25800.1435461123. The cubic root of 665647407 is about 873.1350349882.

The spelling of 665647407 in words is "six hundred sixty-five million, six hundred forty-seven thousand, four hundred seven".