640560673 has 4 divisors (see below), whose sum is σ = 640719940. Its totient is φ = 640401408.

The previous prime is 640560653. The next prime is 640560689. The reversal of 640560673 is 376065046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 110502144 + 530058529 = 10512^2 + 23023^2 .

It is a cyclic number.

It is not a de Polignac number, because 640560673 - 2¹³ = 640552481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640560653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 73440 + ... + 81697.

It is an arithmetic number, because the mean of its divisors is an integer number (160179985).

Almost surely, 2^640560673 is an apocalyptic number.

It is an amenable number.

640560673 is a deficient number, since it is larger than the sum of its proper divisors (159267).

640560673 is a wasteful number, since it uses less digits than its factorization.

640560673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159266.

The product of its (nonzero) digits is 90720, while the sum is 37.

The square root of 640560673 is about 25309.3001286089. The cubic root of 640560673 is about 862.0254553451.

The spelling of 640560673 in words is "six hundred forty million, five hundred sixty thousand, six hundred seventy-three".