640940240 has 40 divisors (see below), whose sum is σ = 1491252768. Its totient is φ = 256192640.

The previous prime is 640940231. The next prime is 640940257. The reversal of 640940240 is 42049046.

640940240 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191219 + ... + 194541.

Almost surely, 2^640940240 is an apocalyptic number.

It is an amenable number.

640940240 is an abundant number, since it is smaller than the sum of its proper divisors (850312528).

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

640940240 is a wasteful number, since it uses less digits than its factorization.

640940240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5747 (or 5741 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 640940240 is about 25316.7975857927. The cubic root of 640940240 is about 862.1956873641.

Adding to 640940240 its reverse (42049046), we get a palindrome (682989286).

The spelling of 640940240 in words is "six hundred forty million, nine hundred forty thousand, two hundred forty".