640018840 has 64 divisors (see below), whose sum is σ = 1473500160. Its totient is φ = 250124160.

The previous prime is 640018811. The next prime is 640018853. The reversal of 640018840 is 48810046.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 350169 + ... + 351991.

It is an arithmetic number, because the mean of its divisors is an integer number (23023440).

Almost surely, 2^640018840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640018840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (736750080).

640018840 is an abundant number, since it is smaller than the sum of its proper divisors (833481320).

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

640018840 is a wasteful number, since it uses less digits than its factorization.

640018840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2032 (or 2028 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 31.

The square root of 640018840 is about 25298.5936368012. The cubic root of 640018840 is about 861.7823320859.

Adding to 640018840 its reverse (48810046), we get a palindrome (688828886).

The spelling of 640018840 in words is "six hundred forty million, eighteen thousand, eight hundred forty".