640660047 has 8 divisors (see below), whose sum is σ = 855536256. Its totient is φ = 426445272.

The previous prime is 640660019. The next prime is 640660091. The reversal of 640660047 is 740066046.

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

It is not a de Polignac number, because 640660047 - 2⁶ = 640659983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640660747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 163093 + ... + 166974.

It is an arithmetic number, because the mean of its divisors is an integer number (106942032).

Almost surely, 2^640660047 is an apocalyptic number.

640660047 is a deficient number, since it is larger than the sum of its proper divisors (214876209).

640660047 is a wasteful number, since it uses less digits than its factorization.

640660047 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330717.

The product of its (nonzero) digits is 24192, while the sum is 33.

The square root of 640660047 is about 25311.2632438604. The cubic root of 640660047 is about 862.0700300912.

The spelling of 640660047 in words is "six hundred forty million, six hundred sixty thousand, forty-seven".