640513565 has 8 divisors (see below), whose sum is σ = 768846168. Its totient is φ = 512257600.

The previous prime is 640513543. The next prime is 640513567. The reversal of 640513565 is 565315046.

It can be written as a sum of positive squares in 4 ways, for example, as 27604516 + 612909049 = 5254^2 + 24757^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 640513565 - 2¹⁰ = 640512541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640513567) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1199 + ... + 35811.

It is an arithmetic number, because the mean of its divisors is an integer number (96105771).

Almost surely, 2^640513565 is an apocalyptic number.

It is an amenable number.

640513565 is a deficient number, since it is larger than the sum of its proper divisors (128332603).

640513565 is a wasteful number, since it uses less digits than its factorization.

640513565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38319.

The product of its (nonzero) digits is 54000, while the sum is 35.

The square root of 640513565 is about 25308.3694654555. The cubic root of 640513565 is about 862.0043231857.

The spelling of 640513565 in words is "six hundred forty million, five hundred thirteen thousand, five hundred sixty-five".