640555047 has 48 divisors (see below), whose sum is σ = 1071278208. Its totient is φ = 379118880.

The previous prime is 640555031. The next prime is 640555061. The reversal of 640555047 is 740555046.

It is a happy number.

640555047 is a `hidden beast` number, since 64 + 0 + 5 + 550 + 47 = 666.

It is not a de Polignac number, because 640555047 - 2⁴ = 640555031 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640555007) 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 47 ways as a sum of consecutive naturals, for example, 112153 + ... + 117725.

It is an arithmetic number, because the mean of its divisors is an integer number (22318296).

Almost surely, 2^640555047 is an apocalyptic number.

640555047 is a deficient number, since it is larger than the sum of its proper divisors (430723161).

640555047 is a wasteful number, since it uses less digits than its factorization.

640555047 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5642 (or 5630 counting only the distinct ones).

The product of its (nonzero) digits is 84000, while the sum is 36.

The square root of 640555047 is about 25309.1889834503. The cubic root of 640555047 is about 862.0229316344.

Subtracting 640555047 from its reverse (740555046), we obtain a palindrome (99999999).

The spelling of 640555047 in words is "six hundred forty million, five hundred fifty-five thousand, forty-seven".