640938670 has 16 divisors (see below), whose sum is σ = 1155727440. Its totient is φ = 255922624.

The previous prime is 640938659. The next prime is 640938673. The reversal of 640938670 is 76839046.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640938673) 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, 50632 + ... + 62011.

It is an arithmetic number, because the mean of its divisors is an integer number (72232965).

Almost surely, 2^640938670 is an apocalyptic number.

640938670 is a deficient number, since it is larger than the sum of its proper divisors (514788770).

640938670 is a wasteful number, since it uses less digits than its factorization.

640938670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113219.

The product of its (nonzero) digits is 217728, while the sum is 43.

The square root of 640938670 is about 25316.7665786925. The cubic root of 640938670 is about 862.1949833732.

The spelling of 640938670 in words is "six hundred forty million, nine hundred thirty-eight thousand, six hundred seventy".