640844525 has 12 divisors (see below), whose sum is σ = 795520884. Its totient is φ = 512112000.

The previous prime is 640844471. The next prime is 640844549. The reversal of 640844525 is 525448046.

It can be written as a sum of positive squares in 6 ways, for example, as 51423241 + 589421284 = 7171^2 + 24278^2 .

It is not a de Polignac number, because 640844525 - 2¹² = 640840429 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 11 ways as a sum of consecutive naturals, for example, 9905 + ... + 37145.

It is an arithmetic number, because the mean of its divisors is an integer number (66293407).

Almost surely, 2^640844525 is an apocalyptic number.

It is an amenable number.

640844525 is a deficient number, since it is larger than the sum of its proper divisors (154676359).

640844525 is a wasteful number, since it uses less digits than its factorization.

640844525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28192 (or 28187 counting only the distinct ones).

The product of its (nonzero) digits is 153600, while the sum is 38.

The square root of 640844525 is about 25314.9071694921. The cubic root of 640844525 is about 862.1527664783.

The spelling of 640844525 in words is "six hundred forty million, eight hundred forty-four thousand, five hundred twenty-five".