640889639 has 8 divisors (see below), whose sum is σ = 700491120. Its totient is φ = 582759936.

The previous prime is 640889611. The next prime is 640889657. The reversal of 640889639 is 936988046.

640889639 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 640889639 - 2⁸ = 640889383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640882639) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 367034 + ... + 368775.

It is an arithmetic number, because the mean of its divisors is an integer number (87561390).

Almost surely, 2^640889639 is an apocalyptic number.

640889639 is a deficient number, since it is larger than the sum of its proper divisors (59601481).

640889639 is a wasteful number, since it uses less digits than its factorization.

640889639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 735889.

The product of its (nonzero) digits is 2239488, while the sum is 53.

The square root of 640889639 is about 25315.7982098136. The cubic root of 640889639 is about 862.1729972029.

The spelling of 640889639 in words is "six hundred forty million, eight hundred eighty-nine thousand, six hundred thirty-nine".