640440042 has 32 divisors (see below), whose sum is σ = 1402557120. Its totient is φ = 193345920.

The previous prime is 640440041. The next prime is 640440061. The reversal of 640440042 is 240044046.

640440042 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×640440042³ (a number of 27 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 640439994 and 640440021.

It is not an unprimeable number, because it can be changed into a prime (640440041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 283 + ... + 35790.

It is an arithmetic number, because the mean of its divisors is an integer number (43829910).

Almost surely, 2^640440042 is an apocalyptic number.

640440042 is an abundant number, since it is smaller than the sum of its proper divisors (762117078).

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

640440042 is a wasteful number, since it uses less digits than its factorization.

640440042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36358.

The product of its (nonzero) digits is 3072, while the sum is 24.

The square root of 640440042 is about 25306.9168805684. The cubic root of 640440042 is about 861.9713394612.

Adding to 640440042 its reverse (240044046), we get a palindrome (880484088).

The spelling of 640440042 in words is "six hundred forty million, four hundred forty thousand, forty-two".