640521018 has 24 divisors (see below), whose sum is σ = 1389075168. Its totient is φ = 213310152.

The previous prime is 640521017. The next prime is 640521031. The reversal of 640521018 is 810125046.

640521018 is a `hidden beast` number, since 640 + 5 + 2 + 1 + 0 + 18 = 666.

640521018 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 640520982 and 640521000.

It is not an unprimeable number, because it can be changed into a prime (640521017) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4371 + ... + 36057.

It is an arithmetic number, because the mean of its divisors is an integer number (57878132).

Almost surely, 2^640521018 is an apocalyptic number.

640521018 is an abundant number, since it is smaller than the sum of its proper divisors (748554150).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640521018 is a wasteful number, since it uses less digits than its factorization.

640521018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32818 (or 32815 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 640521018 is about 25308.5167088077. The cubic root of 640521018 is about 862.0076665931.

The spelling of 640521018 in words is "six hundred forty million, five hundred twenty-one thousand, eighteen".