640044040 has 32 divisors (see below), whose sum is σ = 1453567680. Its totient is φ = 253623232.

The previous prime is 640044037. The next prime is 640044043. The reversal of 640044040 is 40440046.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (640044037) and next prime (640044043).

It is not an unprimeable number, because it can be changed into a prime (640044043) 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, 70492 + ... + 79051.

It is an arithmetic number, because the mean of its divisors is an integer number (45423990).

Almost surely, 2^640044040 is an apocalyptic number.

It is an amenable number.

640044040 is an abundant number, since it is smaller than the sum of its proper divisors (813523640).

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

640044040 is a wasteful number, since it uses less digits than its factorization.

640044040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149661 (or 149657 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 640044040 is about 25299.0916832996. The cubic root of 640044040 is about 861.7936424976.

Adding to 640044040 its reverse (40440046), we get a palindrome (680484086).

The spelling of 640044040 in words is "six hundred forty million, forty-four thousand, forty".