664620565 has 24 divisors (see below), whose sum is σ = 934575192. Its totient is φ = 452390400.

The previous prime is 664620511. The next prime is 664620571. The reversal of 664620565 is 565026466.

It can be written as a sum of positive squares in 4 ways, for example, as 321489 + 664299076 = 567^2 + 25774^2 .

It is not a de Polignac number, because 664620565 - 2¹⁵ = 664587797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23665 + ... + 43465.

It is an arithmetic number, because the mean of its divisors is an integer number (38940633).

Almost surely, 2^664620565 is an apocalyptic number.

It is an amenable number.

664620565 is a deficient number, since it is larger than the sum of its proper divisors (269954627).

664620565 is a wasteful number, since it uses less digits than its factorization.

664620565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19957 (or 19950 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 40.

The square root of 664620565 is about 25780.2359376325. The cubic root of 664620565 is about 872.6858316335.

The spelling of 664620565 in words is "six hundred sixty-four million, six hundred twenty thousand, five hundred sixty-five".